In the Sky This Month – November 2009

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of November 2009. Jupiter continues its reign as not only king of the planets but king of the evening sky. November also brings the Leonids which may put on a good show for some observers this year.

Note: If anyone has pictures or observations of these objects/events and want to share them, send me a comment and I’ll post them on the blog.

Planets

Jupiter - Jupiter continues to dominate the evening sky. At magnitude -2.4, Jupiter is ~10 times brighter than the brightest stars in the sky this month. Of all the planets, only Venus, and on very rare occasions Mars, are brighter.

Jupiter is located high in the southern sky by the end of dusk for easy observation. As has been the case all year, it is slowly moving through the southern constellation of Capricornus.

Nov 23 - Moon passes 3° from Jupiter

Neptune – For those with a telescope or binoculars and a dark sky, Neptune is located within 1/2 to 3/4 degrees of Jupiter. Jupiter will be a bright magnitude -2.4 while Neptune will be a faint +7.9. Even Jupiter’s 4 large Galilean moons are about a dozen times brighter than Neptune even though they are much smaller. The big reason for the faintness of Neptune is its distance from both the Earth and Sun. It is roughly 6 times further away from us and the Sun as Jupiter. The distance also explains its apparent small size of 2.3″. A good sized telescope will be required to see Neptune as anything other than a faint star.

Uranus – Uranus is located in western Pisces and is bright enough to be seen in small binoculars at magnitude +5.8 but will still require a telescope in order to see it as anything other than a star (it’s disk is only 3.5″ across).

Mars – Mars can be seen rising in the eastern sky late in the evening (~11 pm at the start of the month and ~9 pm at the end of the month). Mars is rapidly brightening and will reach magnitude 0.0 by the end of the month, matching that of many of the brightest stars visible in the morning sky. Mars will continue to brighten as it approaches its opposition on Jan 29 of next year. This month Mars marches through eastern half of the constellation of Cancer.

Nov 9 – Moon passes close (3°) to Mars

Venus - Venus rises an hour before dawn. When it is visible it is easily the brightest “star” in the sky. It was at its highest in the morning sky back in August and is continuing its slow crawl lower. It is located just above the horizon in the ESE sky right before the start of dawn. For binocular and telescope users, Venus will appear nearly full and is much smaller than it appeared this spring (now 11″ across versus 50″ last spring).

Nov 15 – Moon passes 6° from Venus

Mercury - Mercury starts the month behind the Sun with superior conjunction occurring on November 5. For the rest of the month, Mercury slowly pulls away from the Sun into the evening sky. Southern hemisphere observers will be able to catch a glimpse of Mercury low in the WSW sky during evening twilight. Northern observers will have to wait till December for their chance at seeing Mercury again.

Nov 5 – Mercury at superior conjunction

Saturn – Saturn is easy to observe during the last few hours of the night. Located in Virgo at magnitude +1.0, Virgo only rises right before the start of dawn. Telescope users should note that Saturn’s rings are still close to edge-on.

Nov 12 – Moon and Saturn within 7° of each other

Meteors

November hosts the sometimes great Leonids. In addition, the background rate of meteors is near an annual high. The year is usually split in 2 with January through June having low rates with few major showers while July through December (really through the 1st week of January) have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During November, 12 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Leonids (LEO)

The Leonids have produced some of the most spectacular meteor displays in history. Rates as high as ~70,000 meteors per hour (that’s ~20 meteors per second) were seen in 1833 and 1966. Every ~33 years, the parent comet of the Leonids, Comet Tempel-Tuttle, returns to the vicinity of the Earth. For a few years after Tempel-Tuttle’s last perihelion in 1998, the Leonids produced enhanced rates of meteors as high as 100s to 1000s of meteors per hour.

What will 2009 bring? In a normal year, the Leonids produce maximum rates of ~10-15 meteors per hour. This year there are a number of predictions of enhanced activity.

J. Vaubaillon presents his predictions for this year’s Leonids at the website of the L’Institut de Mécanique céleste et de calcul des éphémérides (IMCCE). The Earth will encounter 4 dense dust trails produced by the Leonid parent comet. On November 17 at ~21:43 UT (or half an hour to an hour later), the Earth will encounter a trail produced in 1466 which may produce as many as ~115 meteors per hour from a dark site. At nearly the same time, November 17 at 21:50 UT, the 1533 trail may produce 80 meteors per hour. Combined the 2 trails may (may being the important word) produce ~200 meteors per hour. A display this strong would not be considered a “storm” but would be better than the Perseids or Geminids at their best by nearly a factor of 2. The predicted times favor observers in central Asia. Unfortunately for those of us in the US, we will miss out.

Two weaker and much more uncertain trails will be observable from the Western hemisphere. On November 17 at ~7:27 UT, the 1567 trail may produce 25 meteors per hour. Since this is in addition to the usual background rate of Leonids may result in total rates of 35-50 per hour which is comparable to last month’s Orionids. Also on November 18 at ~3:29 UT, the very old 1102 trail may enhance activity by 10-50 meteors per hour.

What does this mean? Most of us, especially in the United States, will only see the “normal” maximum on the morning of November 17 with hopefully an extra dozen or two meteors per hour from the 1567 trail. For those located in central Asia, a very good shower may be visible. The Leonids are best observed in the hours before sunrise. They will appear to radiate from the western part of the constellation of Leo.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Starting this month, info on most of the minor showers will be provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Northern and Southern Taurids (NTA/STA)

The Taurids never produce more than ~5 meteors per hour. They make up for their low rates by being active for over two months and by producing many bright fireballs. Their fireballs are more apparent to the average observer because, unlike most meteor showers, the Taurids are observable all night long rather than just in the morning. There is a chance that the Taurids will produce a higher number of fireballs this year than usual. There is a good chance that most fireballs being reported this month will be Taurids. They are active for the entire month of November with the northern branch (NTA) peaking around November 14. Though named after the constellation of Taurus, theTaurids radiate from a point between the constellations of Taurus and Aries this month.

The Taurids are produced by Comet 2P/Encke. Encke is an enigmatic object with the shortest period for any known comet at 3.3 years. First observed in 1786, it has been observed over ~60 orbits and has been seen every year since 1993.

Additional information on these showers and other minor showers not included here can be found at the following sites: Robert Lunsford’s Meteor Activity Outlook, Wayne Hally’s and Mark Davis’s NAMN Notes, and the International Meteor Organization’s 2008 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V = 6.0 – 8.0)

None

Small Telescope Comets (V = 8.0 – 10.0)

Comet 88P/Howell

P/Howell is an evening comet and currently the brightest in the sky. Howell is a short-period comet and takes only 5.49 years to orbit the Sun. Ellen Howell was a student at Caltech when she found the comet on photographic plates taken on 1981 August 29 with the 48″ Palomar schmidt.

In 1981 the comet was on an orbit that never brought it closer to the Sun than 1.62 AU (perihelion distance). As a result, it never got very bright. A relatively close approach to Jupiter in 1990 changed its perihelion distance to 1.40 AU. Further perturbations by Jupiter have decreased its perihelion distance to 1.36 AU. The closer perihelion distance allows the comet to get bright enough for small backyard telescopes. In addition, the comet seems to be running about ~2 magnitude brighter than usual. No obvious reason for the additional brightening has been observed yet.

This year perihelion occurred on Oct 12 so the comet is currently moving away from the Sun and should be fading. A day after perihelion I observed the comet from Tucson with a 12″ dobsonian. The comet was very difficult to observe from the city. At the time, I estimated its brightness at magnitude 8.5. The comet should be a little fainter (from 8.8 to 9.5) this month. The comet is located low in the southwest sky after dusk and will spend most of the month in Sagittarius. At mid-month P/Howell will be 1.41 AU from the Sun and 1.79 AU from Earth.

A finder chart for Comet Howell can be found at Comet Chasing and Aktuelle Kometen (in German).

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Comet C/2006 W3 (Christensen)

This comet was discovered nearly 3 years ago on 2006 November 18 by Eric Christensen of the Catalina Sky Survey north of Tucson. At the time the comet was located 8.7 AU from the Sun which is nearly the distance of Saturn.

The comet reached perihelion at a rather distant 3.12 AU from the Sun on 2009 July 6. Because of its large perihelion distance, the comet will only slowly move away from the Sun and, though it will slowly fade, it should remain bright enough to be seen in modest sized backyard telescopes this month.

At mid-month, the comet is 3.37 AU from the Sun and 3.82 AU from Earth. Though observed as bright as magnitude ~8.2 it is now around magnitude 9.5 to 10.0. It is moving southeast while paralleling the summer Milky Way. This month the comet can be found in southern Aquila near the Sagittarius and is well placed for evening observing. This will probably be the last month that this comet will be observable in small scopes.

A finder chart for Comet Christensen can be found at Comet Chasing and Aktuelle Kometen (in German).

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Comet 217P/LINEAR

217P/LINEAR is also a short-period comet though it takes a little longer than Howell to circle the Sun, 7.83 years versus 5.49 years. P/LINEAR also comes closer to the Sun with perihelion at 1.22 AU from the Sun. The comet is already a month past perihelion which occurred on Sept 8.

P/LINEAR was first observed by the Lincoln Near Earth Asteroid Research (LINEAR) survey on 2001 June 21 though it wasn’t until 2001 July 11 that it was recognized as a comet. The 2009 apparition is the first return since the discovery apparition.

Though P/LINEAR and P/Howell have similar perihelion distances, LINEAR is a much fainter (or less active) comet. While Howell is ~9th magnitude at a rather distant 1.65 AU from Earth, P/LINEAR is a little fainter at magnitude ~10.0 though it is much closer (0.61 AU from Earth). This may be the last time to see P/LINEAR in small backyard telescopes until its 2048 return when it will pass within 0.40 AU of Earth. All the returns between 2009 and 2048 will be more distant.

I was able to observe 217P/LINEAR with 30×125 binoculars on the morning of Sept 25. In order to see the comet I had to drive out to a dark site. The comet was a rather nondescript smudge about 1.5′ across and with a brightness of magnitude 10.1. On Oct 16, I dragged my 12″ dob to a dark site. The comet was easy to observe with a nice short 0.08° long tail. At that time, the estimated brightness was magnitude 9.9.

This month the comet will be visible in the morning sky in the faint Milky Way constellation of Monoceros. It should remain at magnitude ~10 or a little fainter for the entire month. At mid-month the comet will be 1.49 AU from the Sun and 0.64 AU from Earth.

A finder chart for Comet LINEAR can be found at Comet Chasing and Aktuelle Kometen (in German).

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Comet C/2007 Q3 (Siding Spring)

This long-period was first seen on 2007 August 25 by Donna Barton of the Siding Spring Survey in Australia. This past Oct. 7th the comet reached a rather distant perihelion at 2.25 AU from the Sun. Unfortunately, the comet and Earth are located on opposite sides of the Sun so the comet is rather far from Earth. Still the comet is observable before the start of dawn as a ~9.0 to 9.5 magnitude comet near the Leo/Virgo border. At mid-month the comet is 2.30 AU from the Sun and 2.71 AU from Earth.

A finder chart for Comet Siding Spring can be found at Comet Chasing and Aktuelle Kometen (in German).

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Asteroids

Binocular and Small Telescope Asteroids (V < 9.0)

(3) Juno

Juno was the 3rd asteroid to be discovered after (1) Ceres and (2) Pallas. It was found by German astronomer Karl Harding on September 1, 1804. With dimensions of 320×267×200 km (192 x 160 x 120 miles) Juno ranks as the 10th largest asteroid in the Main Belt though it is the 2nd largest stony S-type asteroid.

This month it will be moving slowly southwestward in Aquarius. Peak brightness occurred at opposition on Sept. 22 when Juno was as bright as magnitude 7.6. In November it will fade from magnitude 8.4 to 8.9. Twenty degrees or so to the east of Juno is another bright asteroid, (18) Melpomene which is described in its own section.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Juno from Heavens Above.

(18) Melpomene

About 25 degrees to the east of (3) Juno lies another nice asteroid target for small telescopes. (18) Melpomene is located in the constellation of Cetus and is roughly the same brightness as Juno, in November it will fade from magnitude 8.3 to 9.0.

Melpomene is another stoney S-type asteroid and similar to Iris was also discovered by John Russel Hind. Found in 1852, it is his 5th of 10 asteroid discoveries.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Iris from Heavens Above.

(4) Vesta

Though not as large as Ceres, Vesta is more reflective making it the brightest asteroid in the Main Belt. Vesta is peculiar in that it appears to have evidence of volcanism on its surface. Similar to the Moon, Vesta may be covered with large expanses of frozen lava flows. It is classified as a V-type asteroid and is the only large asteroid with this classification. Many of the smaller V-type asteroids are chips of Vesta blasted off it by past asteroid and comet impacts. Vesta is similar in size to Pallas with dimensions of 347×336x275 miles or 578×560×458 km. Vesta will also be visited by NASA’s Dawn spacecraft which will arrive in 2010.

Vesta is once again observable in the morning sky before the start of dawn. It is brightening from magnitude 8.1 to 7.7 as it travels eastward just north of Regulus in Leo.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Vesta from Heavens Above.

The Discovery, Re-discovery and Recovery of Comet Pigott-LINEAR-Kowalski

There has been a long held rule that comets can not be named after more than 3 discoverers. In the days of slow world-wide communications, it was not uncommon for a comet to be discovered by numerous observers before the official discovery announcement could be made. As a result, many comets had three names attached to them. With the internet, the frequency of triple named comets has decreased. The latest comet to bear three names is Comet Pigott-LINEAR-Kowalski and 226 years passed between the time it acquired its first and third name.

Edward Pigott of York, England first spotted Comet Pigott on November 19, 1783. Astronomy ran in the Pigott family as his father was also a well known astronomer. The comet was lost after the 1783 apparition. Due to the primitive state of measuring comet positions as well as orbit determination, it was not unusual for comets to be lost until rediscovered at a later time.

That later time came in January of 2003 when the LINEAR survey found a “new” comet with their telescopes outside of Socorro, New Mexico. Within days of its discovery the LINEAR comet, now designated Comet C/2003 A1 (LINEAR), a suggestion was made that it might be a return of long-lost Comet Pigott. Unfortunately, it was not possible to made a definite link between the 2003 LINEAR comet and Piggot’s 1783 find. The comet would have to wait till it was observed at yet another apparition.

A few weeks ago on the night of Sept 10, Rich Kowalski of the Catalina Sky Survey was surveying the sky for unknown comet and asteroids when he came across a possible new comet. Rich shared some of his thoughts on his latest comet find:

The Catalina Sky Survey, along with most of the observatories in the American Southwest, do not observe during July & August each year due to our rainy season, known locally as the Monsoon. It gives us the time to repair and maintain our telescopes and upgrade instruments and facilities. Time that is precious and isn’t used for these things during the other ten months of the year which is our “Observing Season”.

This year’s season started right after the Full Moon of September and as luck would have it the first night was rainy and cloudy. Even though I was at the Catalina Schmidt telescope, I could not observe. The second night of my run and the actual first night of the new season was much better. I could observe most of the night, even though some clouds remained during the first few hours. It wasn’t long before I discovered a new Near-Earth Asteroid, 2009 RH, a small rock only about 50 meters (150 feet) across. The rest of the night continued with our normal pattern of observing various parts of the sky systematically, looking for these asteroids.

A few hours before dawn, with the waning gibbous moon climbing high in the sky, our software showed me an object that was faint and very diffuse, almost a wisp of light like the reflections off the optics we sometimes see when there is a bright star close by, but this one was different. It isn’t uncommon for us to spot comets on our nightly search and after a while your eye becomes trained to see the differences between asteroids, galaxies, reflections in the optics and comets. This one looked like a puffball of a comet, with no tail or the central condensation that many comets have, but I knew right a way it was a comet. As I said, spotting comets is not out of the ordinary and almost every time we see one the comet is already know. I copied the coordinates of this comet into the Minor Planet Center’s “Comet Checker” web page, fully expecting it to identify the comet just as it had done several times before during that same night.

This time it did not come back with an ID.

“Oh really?” I thought to myself.

It had been nearly two years since my last comet discovery, P/2007 T2, a comet I discovered on my birthday. After seeing that it was not identified, I took a closer look to make sure it was actually a comet before reporting it to the MPC and the Central Bureau for Astronomical Telegrams (CBAT). CBAT is the clearinghouse for reporting comet discoveries, just as the MPC is the clearinghouse for positional observations and discoveries of asteroids and planetary satellites.

I then proceeded to have our software schedule additional observations of the comet later that night and continued searching for more NEOs. I secured these observations before the sky started getting bright from the coming dawn.

The next night was mostly clear again and I continued the search for more NEOs. By the time this new comet rose high enough in my sky for me to observe it again, no other observations had been reported, so I made some additional ones to confirm it was real and to help determine it’s orbit. Before the night was over a few other observatories had reported additional observations.

When the Circular announcing the discovery of the comet was released I was a bit surprised that it had been determined by Dimitry Chestnov, an astronomer in Moscow, that this comet was actual the return of an object that was found by a fellow NEO survey in New Mexico called LINEAR in 2003. It was also thought that it might also be the comet Edward Pigott discovered in 1783, but no one could be sure. After my discovery, the two objects, my comet and the one found by LINEAR were clearly one and the same, but its position was very far off from where it should have been in the sky. It was found that this comet had a close encounter with Jupiter exactly three years to the day before I picked it up with the Catalina Schmidt. The recent observations, along with those made in 2003 made it obvious that this was indeed the comet that Pigott had discovered in 1783 and had been lost for 226 years!

It was an interesting and exciting way to start off the new observing season and whets my appetite to the other things my colleagues and I will discover in the coming year!

With the identification of the latest Kowalski comet with P/2003 A1 (LINEAR), it was possible to link the comet with the 1783 Pigott comet. The comet is now known as P/2009 R2 (Pigott-LINEAR-Kowalski) and will probably be officially numbered as comet 226P/Pigott-LINEAR-Kowalski.

Though the comet was bright enough to allow small telescope users to see it in 1783, it no longer gets as bright. It is likely that the comet was in outburst in 1783 which caused it to get brighter than usual. Also in 1783 the comet approached within 1.46 AU of the Sun. Now the comet only approaches within 1.77 AU of the Sun. Since it is 4 months past perihelion the comet barring another outburst will slowly fade from its current brightness of 17th magnitude.

The 4 recovery images of Comet Pigott-LINEAR-Kowalski taken by Rich Kowalski at the Catalina Sky Survey on 2009 Sept 10. The comet is located within the small purple circle. Credit: Rich Kowalski/Catalina Sky Survey/NASA

Now’s the Time to See Comet Christensen

The brightest comet in the sky is Comet C/2006 W3 (Christensen). Now is the best time to observe this comet as it is nicely located in the evening sky after the end of twilight. At 8th magnitude the comet is not bright enough to be seen with just the naked eye. It will require a small telescope, though observers at very dark sites can probably see the comet with small binoculars. Though the comet will be observable over the next month or three, it is slowly fading and getting lower in the sky.

Moving through the constellation Aquila, the comet is located near the meridian, or due south, at the end of evening twilight. It is a few degrees to the southwest of Altair, the brightest star in Aquila and the southernmost star in the Summer Triangle. The comet is equally visible from both the northern and southern hemispheres. Recent observations put the comet near magnitude 8.5. It’s brightness should remain fairly steady for the rest of the month.

Ephemerides for the comet can be found at the Minor Planet Center.

Another version of its sky chart can be found at Comet Chasing.

Chart of the location of Comet C/2006 W3 (Christensen) for the 2nd half of September. Chart created with C2A. Credit: Carl Hergenrother/C2A

The comet was discovered by Eric Christensen of the Catalina Sky Survey on 2006 November 18. He used the 0.68-m Catalina Schmidt telescope located near Mount Bigelow in the Catalina Mountains north of Tucson. It was the 15th of Eric’s 19 comet discoveries. At discovery the comet was located 8.00 AU from Earth and 8.66 AU from the Sun which is almost as far from the Sun as Saturn (9.8 AU). Though such a large discovery distance is not rare these days it is still impressive since only a small fraction of all comets are discovered out that far.

Eric shared some thoughts on his discovery: “Regarding C/2006 W3, I honestly can’t recall much about its discovery. Perhaps the only remarkable thing about it was that it was so unremarkable at the time: small, faint, diffuse, and without any obvious tail or structure. When the initial MPEC came out I remember being excited by how distant it was and how close it was predicted to come (q~1.5), though this of course was quickly modified to a “disappointing” q~3.1.

It’s a little ironic that less than 6 months after discovery, I had moved to the southern hemisphere where C/2006 W3 would remain hidden from view until pretty recently. I’m embarrassed to admit that I haven’t yet seen it visually through even a small telescope…and unfortunately there’s no eyepiece on Gemini. “

As Eric mentioned, right after discovery the original orbit had the comet coming much closer to the Sun at perihelion. After a week or 2 of further observations the perihelion distance was moved farther away. This is common with distant comets. It’s not that the orbit is actually changing but rather that we don’t have sufficient observations to accurately determine the orbit. In the movies, the astronomer discovers something and then after a few furious seconds of keystrokes knows exactly where the object is going. In real life it may take hours (for very close objects) to years (for objects out by Pluto) of additional observations to nail down the correct orbit.

Comet Christensen is a long-period comet taking ~100,000 years or more to orbit the Sun. Closest approach to the Sun (perihelion) occurred on 2009 July 6 at 3.13 AU from the Sun. The comet’s orbit is highly inclined to the plane of the solar system at an angle of 127° which is slightly retrograde (meaning it orbits in the opposite direction as the planets).

Orbit of Comet Christensen. Positions valid for 2009 Sept 16. Chart made with C2A. Credit: Carl Hergenrother/C2A

Back in May of this year I was able to observe Comet Christensen with the 61″ telescope near Mount Bigelow (located at the same site as the Catalina Schmidt telescope that was used to discover the comet). At the time the comet was roughly the same brightness as it is now. Processing the image to look for structure in the inner coma revealed a few jets (the insert image in the figure below).  This is somewhat surprising for such a distant comet. Usually only comets that are much closer to the Sun display jet activity.

For another view of the comet, Salvador Aguirre of Hermosillo, Mexico submitted drawings of the comet as seen through his small backyard telescope. As his drawings show the comet does not have much of a tail and looks like a small faint smudge on the sky.

Small telescope observation of Comet Christensen. Credit: Salvador Aguirre

I’d like to thank Eric for sending his recollections and Salvador for sending his observations.

If anyone has pictures or drawings of this or any other comet to share, I’d like to post them.

In The Sky This Month – September 2009

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of September 2009. Jupiter continues its reign as not only king of the planets but king of the evening sky.

Note: If anyone has pictures or observations of these objects/events and want to share them, send me a comment and I’ll post them on the blog.

Planets

Jupiter -Jupiter continues to dominate the evening sky. Based on the comments left on this blog, many people have been noticing Jupiter in the southeast sky during the evening. At magnitude -2.8, Jupiter is ~13 times brighter than the brightest stars in the sky this month. Of all the planets, only Venus, and on very rare occasions Mars, are brighter.

Jupiter is already located high enough in the southest sky by the end of dusk for easy observation. Due to Jupiter’s location in the southern constellation of Capricornus , it never gets very high above the southern horizon this year.

Aug 2 – Nearly Full Moon passes within 3° of Jupiter and Neptune
Aug 29 – Moon within 3° of Jupiter

Chart of the sky during the middle of September showing the position of Jupiter. Chart created with Stellarium (www.stellarium.org).

Neptune – For those with a telescope or binoculars and a dark sky, Neptune is located within 1/2 to 3/4 degrees of Jupiter. Jupiter will be a bright magnitude -2.8 while Neptune will be a faint +7.8. That makes Jupiter over ~17,000 times brighter than Neptune. Even Jupiter’s 4 large Galilean moons are about a dozen times brighter than Neptune even though they are much smaller. The big reason for the faintness of Neptune is its distance from both the Earth and Sun. It is roughly 6 times further away from us and the Sun as Jupiter. The distance also explains its apparent small size of 2.3″. A good sized telescope will be required to see Neptune as anything other than a faint star.

Though Neptune wasn’t discovered until 1846, it was actually observed by Galileo on two occasions in 1612 and 1613. Similar to this month’s circumstances, Jupiter was passing very close to Neptune. Galileo observed and recorded Neptune as a star in the vicinity of Jupiter. There is also evidence that he noticed that Neptune had moved but didn’t follow up on it. So when you observe these 2 planets imagine what Galileo must have been thinking nearly 400 years ago.

Uranus – This month Uranus is at opposition which means it is at its closest to Earth and at its brightest. Uranus is located in western Pisces and is bright enough to be seen in small binoculars at magnitude +5.7 but will still require a telescope in order to see it as anything other than a star (it’s disk is only 3.5″ across).

Sept 17 - Uranus at opposition

Mars – Mars can be seen in the eastern sky during the 2nd half of the might. It rises around midnight though it won’t get high enough to clear most trees and building till about 1-2 am. At magnitude +0.9, its brightness matches those of many of the brightest stars visible in the morning sky. This month Mars marches through the constellation of Gemini. Mars will continue to brighten as it approaches its opposition on Jan 29 of next year.

Sept 13 – Moon within 1.1° of Mars

Chart of the sky on the morning of Sept 16. Chart created with Stellarium (www.stellarium.org).

Venus - Venus is the brightest “star” in the sky a hour or so before dawn. It was at its highest in the morning sky last month but now begins its slow crawl lower though it will remain an easy object for early risers  over the next 2-3 months. For binocular and telescope users, Venus will appear nearly full and is much smaller than it appeared this spring (now 12″ across versus 50″ last spring).

Sept 16 – Moon passes 3° from Venus
Sept 20 – Venus within 0.5° of the 1st mag star Regulus

The Venus-Moon conjunction on the morning of Sept 16. Chart created with Stellarium (www.stellarium.org).

Mercury - For northern observers, Mercury is not visible until the last days of September when it can be seen as a 1st magnitude star rising in the east just before the Sun.

Sept 20 – Mercury at inferior conjunction (located between the Sun and Earth)

Saturn – Saturn is not visible this month as it is located on the opposite side of the Sun from Earth. As a result, it is located too close to the Sun in the sky to be easily observed. This is a shame because on September 4th, Saturn’s rings will be edge-on and would appear as a very thin line or even disappear in telescopes.

Sept 17 – Saturn at conjunction (located on the side of the Sun opposite Earth)

Meteors

September does not have many good showers though the background rate of meteors is near an annual high. The year is usually split in 2 with January through June having low rates with few major showers while July through December (really through the 1st week of January) have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During September, 12 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

None this month.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors.

Aurigids (Max Date = Sept 1, Max ZHR = ~3 per hour)

The Aurigids are active from Aug 25 to Sept 8 with a peak on Sept 1. The shower is created by Comet Kiess, a comet only observed in 1911 though it should be back in ~70 years. The Aurigid shower is a minor one with a peak rate of 5 meteors per hour for observers under very dark skies.

This shower does have a history of producing short but spectacular outbursts. Reported outbursts in 1935, 1986 and 1994 allowed scientists to predict an outburst in 2007. The prediction was so good that the peak time was accurate to ~10 minutes. I was lucky enough to have observed this shower that only lasted for ~1 hour. At its maximum it produced a maximum ZHR of ~130 meteors per hour. Unfortunately no outbursts are predicted over the next 25 years, but you never know…

The shower appears to radiate from a position just to the east of the body of the constellation of Auriga. This shower is sometimes called the Alpha Aurigids.

September Perseids (Max Date = Sept 9, Max Rate = ~5 per hour)

The September Perseids are not related to the great Perseids of August. The showers were created by separate comets. This shower showed little sign of unusual activity until enhanced activity was observed on the night of Sept 9, 2008. That surprise display was also the topic of the very first Transient Sky post.

I have not seen any published research into last year’s high activity so its possible this years may see a repeat. Unfortunately, the moon will be bright and will drown out many fainter meteors.

Delta Aurigids (Max Date = Sept 28, Max Rate = ~3 per hour)

This weak shower appears the overlap the Sept Perseids and for some time they were considered part of the same shower. We now know that the showers come from different (though unknown) comets. The Delta Aurigids radiate from a point north of the body of Auriga and the bright star Capella.

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V = 6.0 – 8.0)

None

Small Telescope Comets (V = 8.0 – 10.0)

Comet C/2006 W3 (Christensen)

This comet was discovered over 2 years ago on 2006 November 18 by Eric Christensen of the Catalina Sky Survey north of Tucson. At the time the comet was located at 8.7 AU from the Sun which is nearly the distance of Saturn. The comet continues to move closer to the Sun and Earth and is currently 3.8 AU from the Sun and 3.4 AU from the Earth.

The comet is currently around magnitude 8.2 and should be at its brightest this month.  It is moving southeast while paralleling the summer Milky Way. This month the comet will cross the constellation of Aquilia. The is well placed for evening observing.

The comet reached perihelion at a rather distant 3.12 AU from the Sun on 2009 July 6. Because of its large perihelion distance, the comet will only slowly move away from the Sun and though it will slowly fade from here on out it should remain bright enough to be seen in modest sized backyard telescopes for all of 2009.

A finder chart for Comet Christensen can be found at Comet Chasing and Aktuelle Kometen (in German).

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

22P/Kopff

All of the above comets are long-period comets which will not return to the inner Solar System for thousands to millions of years. Comet Kopff is a frequent visitor with an orbital period of 6.4 years. Discovered on 1906 August 20 by August Kopff of Germany, the comet has been observed during every subsequent return except one.

The comet reached perihelion at 1.58 AU from the Sun on May 25. Though now moving away from the Sun, the comet still moving closer to Earth and will be located 0.78 AU from us at the end of the month. Recent observations place the comet at magnitude 9.5  to 10.5. It is now slowly fading. The comet spends September in Aquarius.

A finder chart for Comet Kopff can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Asteroids

Binocular and Small Telescope Asteroids (V < 9.5)

(3) Juno

Juno was the 3rd asteroid to be discovered after (1) Ceres and (2) Pallas. It was found by German astronomer Karl Harding on September 1, 1804. With dimensions of 320×267×200 km (192 x 160 x 120 miles) Juno ranks as the 10th largest asteroid in the Main Belt though it is the 2nd largest stony S-type asteroid.

This month it will be moving slowly eastward through Pisces. Peak brightness will come at opposition on Sept. 22 when Juno will be as bright as magnitude 7.6. A few degrees to the eats of Juno is another bright asteroid, (18) Melpomene which is described in its own section.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Juno from Heavens Above.

(18) Melpomene

Just a few degrees to the east of (3) Juno lies another nice asteroid target for small telescopes. (18) Melpomene is also located in the constellation of Pisces and is only a little bit fainter than Juno, brightening from magnitude  8.7 to 8.0 in September.

Melpomene is another stoney S-type asteroid and similar to Iris was also discovered by John Russel Hind. Found in 1852, it is his 5th of 10 asteroid discoveries.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Iris from Heavens Above.

In the Sky This Month – August 2009

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of August 2009. The big attraction this month is brilliant Jupiter, visible in the southeast sky during the evening, and the Perseid meteor shower.

Note: If anyone has pictures or observations of these objects/events and want to share them, send me a comment. I’ll post them here.

Planets

Mercury - Mercury is in the midst of a poor evening apparition for northern hemisphere observers. In contrast, southern hemisphere observers will see a great display. Mercury will appear as bright as some of the brightest stars low in the western sky during evening twilight. Only folks with clear views of the horizon have a chance at seeing it. Don’t worry if you can’t, this is Mercury’s worst apparition for northerners and there will be better opportunities.

Aug 2 – Mercury and 1st magnitude star Regulus are within 0.6° of each other
Aug 17 - Mercury and Saturn within 3° of each other
Aug 22 – Moon passes 3° from Mercury

Saturn – This is the last month to see Saturn in the evening sky this year and the last chance to see it at all until November when it will be a morning object. Saturn is located low in the Western sky during twilight. At magnitude +1.1, it is not much brighter than some of the brightest stars in that part of the sky.

For those of you with access to telescopes, you will see that its rings are barely open and almost edge-on. This is the narrowest the rings will appear from Earth for the next 15 years. Though the rings are over 70,000 kilometers (43,500 miles) wide, they are only 10 meters (33 feet) thick. Since the rings are seen edge, or width, on during ring plane crossings, they can actually appear to disappear in most telescopes. The last time this happened was in 1995. This year the crossing happens on Sept 4 when Saturn is too close to the Sun to be observed. Still, the rings will appear very narrow and line-like this month.

Aug 17 – Saturn and Mercury within 3° of each other
Aug 22 – Thin crescent Moon within 6° of Saturn

Jupiter and Neptune -Jupiter is the planet highlight of the month. Based on the comments left on this blog, many people have been noticing Jupiter in the southeast sky during the evening. At magnitude -2.8, Jupiter is ~13 times brighter than the brightest stars in the sky this month. Of all the planets, only Venus, and on very rare occasions Mars, are brighter.

Jupiter rises during evening twilight and is highest in the sky aaround midnight. Due to Jupiter’s location in the southern constellation of Capricornus , it never gets very high this year.

For those with a telescope or binoculars and a dark sky, Neptune is located within 1/2 to 3/4 degrees of Jupiter. Jupiter will be a bright magnitude -2.8 while Neptune will be a faint +7.8. That makes Jupiter over ~17,000 times brighter than Neptune. Even Jupiter’s 4 large Galilean moons are about a dozen times brighter than Neptune even though they are much smaller. The big reason for the faintness of Neptune is its distance from both the Earth and Sun. It is roughly 6 times further away from us and the Sun as Jupiter. The distance also explains its apparent small size of 2.3″. A good sized telescope will be required to see Neptune as anything other than a faint star.

Image of Jupiter by Bob Lunsford from early May 2009. Note one of its moons near the left edge.

Though Neptune wasn’t discovered until 1846, it was actually observed by Galileo on two occasions in 1612 and 1613. Similar to this month’s circumstances, Jupiter was passing very close to Neptune. Galileo observed and recorded Neptune as a star in the vicinity of Jupiter. There is also evidence that he noticed that Neptune had moved but didn’t follow up on it. So when you observe these 2 planets imagine what Galileo must have been thinking nearly 400 years ago.

Aug 6 – Full Moon passes within 3° of Jupiter and Neptune
Aug 14 – Jupiter at opposition (meaning Jupiter is closest to Earth, at its brightest for the year and visible all night long)
Aug 17 – Neptune at opposition

Uranus – Uranus is located in western Pisces. It is bright enough to be seen in small binoculars at magnitude +5.8 but will still require a telescope in order to see it as anything other than a star (it’s disk is only 3.5″ across).

Aug 9 – Moon within 5° of Uranus

Mars – Many of you may have received an email or read stories about how Mars is going to be big and bright this month. Some stories suggest that it will rival the Full Moon in size. Well, it’s all bull. This story has been circulating around the internet every year since August of 2003 when Mars did have a closer than usual (but not unusual) approach to Earth. For some reason the email story gets re-circulated every year with only the year changed. Also note that the email was never factual. Even in August of 2003, Mars never got as bright as the Moon. It did get as bright as it ever gets which is a little brighter than Jupiter appears this month.

Mars can be seen in the eastern sky a few hours before sunrise. It rises between 1 and 1:30 am all month long though it won’t get high enough to clear most trees and building till about 3 am. At magnitude +1.1, its brightness matches those of many of the bright stars in the 2 constellations it is moving through this month, Taurus and Gemini.

Aug 16 – Moon within 3° of Mars

Venus - Venus continues to slowly climb higher every night. It is currently a morning object and is best seen an hour before sunrise low in the eastern sky. For Southern Hemisphere observers, it has already peaked for this apparition and is slowly dropping back towards the horizon. For Northern observers, Venus will continue to climb higher until early August. It rises between 3am and 4am for most observers though it will be low in the eastern sky the while time. For binocular and telescope users, Venus is now in a gibbous phase (between half and full) and is slowly shrinking as it moves further away from Earth.

Aug 17 – Moon within 2° of Venus

Meteors

August is one of the best months for meteor activity. The year is usually split in 2 with January through June having low rates with few major showers while July through December (really through the 1st week of January) have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During August, 12 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Perseids (PER) [Date range = July 17 - Aug 24, Max = Aug 12]

The Perseids are one of the best meteor showers of the year and rarely disappoint. This year’s display will bring a mixed bag. On one hand, the Moon will be nearly full and poorly placed. The Moon’s bright light will drown out many of the fainter Perseids bringing the number of visible meteors down significantly. On the other hand, there are predictions that this years’s display will be richer than usual. Meteor stream models predict increased rates around 0800 and 0900 UT on the morning of August 12 (4:00-5:00 EDT, 1:00-2:00 am PDT). The reason is a ribbon, or filament, of dust produced by the Perseid parent Comet Swift-Tuttle in 1610. Some predictions are calling for a ZHR rates of 200 which is twice as good as the usual rates of 60-120. Of course, those rates are only valid for a very dark sky with no Moon. Still rates of 30 per hour may be possible for many non-urban locations.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors.

Southern δ-Aquarids (SDA) [Date range = July 12 - Aug 19, Max = July 28]

The Southern δ-Aquarid shower peaked in late July. There should still be significant activity from this shower in early August. By the middle of the month, all activity should be over. They are part of the Machholz complex of asteroids, comets and meteor showers that are the result of the breakup of a single comet into hundreds of smaller objects over the past thousands of years. The complex includes comet 96P/Machholz, the suspected extinct comet 2003 EH1, hundreds of Marsden and Kracht group comets, and the Quadrantid and Arietid meteor showers.

It is the comets of the Marsden group that are directly resposible for the SDA shower. These small comets have never been observed from Earth. There are only seen by spacecraft that can observe very close to the Sun. Due to the very small perihelion distance of these comets (~0.05 AU) they only get bright enough to be discovered when close to the Sun. Currently there are ~33 comets that are known to be members of the Marsden group.

The shower radiates from RA = 22h 36m, Dec = -16 deg.

Piscis Austrinids (PAU) [Date range = July 15 - Aug 10, Max = July 27]

This shower of unknown parentage is a difficult one for northern observers due to the southern location of its radiant (RA = 22h 44m, Dec = -30deg). Similar to the SDAs and the CAPs below, it is active from mid-July to mid-August with a maximum around July 27. At maximum one can expect 2-4 meteors per hour from a dark site. Rates will be even lower for northern observers.

α-Capricornids (CAP) [Date range = July 3 - Aug 15, Max = July 29]

The CAP is yet another southern shower (RA = 20h 28m, Dec = -10 deg) that is difficult to observe from northern latitudes. With a peak on July 29, it can be expected to produce 3-6 meteors per hour. Unlike the PAUs, the CAPs appear to be associated with a known comet, 169P/NEAT.

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V = 6.0 – 8.0)

None

Small Telescope Comets (V = 8.0 – 10.0)

Comet C/2006 W3 (Christensen)

This comet was discovered over 2 years ago on 2006 November 18 by Eric Christensen of the Catalina Sky Survey north of Tucson. At the time the comet was located at 8.7 AU from the Sun which is nearly the distance of Saturn. The comet continues to move closer to the Sun and Earth and is currently 3.8 AU from the Sun and 3.4 AU from the Earth.

The comet is currently around magnitude 8.2 and should be at its brightest this month.  It is moving southeast while paralleling the summer Milky Way. This month the comet will travel through the constellations of Vulpecula, Sagitta and Aquilia. The comet is best seen after 10 pm.

The comet reached perihelion at a rather distant 3.12 AU from the Sun on 2009 July 6. Becuase of its large perihelion distance, the comet will only slowly move away from the Sun and though it will slowly fade from here on out it should remain bright enough to be seen in modest sized backyard telescopes for all of 2009.

A finder chart for Comet Christensen can be found at Comet Chasing and Aktuelle Kometen (in German).

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Comet C/2008 Q3 (Garradd)

This is the surprise comet of the summer. From time to time what appears to be a faint run-of-the-mill comet will undergo an outburst and brighten substantially. This is the case with Comet Garradd which was discovered by Gordon Garradd of the Siding Spring Survey (Australia). He used the 0.5-m Uppsala schmidt telescope to discover this comet back on 2008 August 27.

The comet was a faint 19th magnitude at discovery. With perihelion expected on 2009 June 23 at 1.80 AU from the Sun, it was expected to brighten but only to about 12th-14th magnitude. Two weeks ago the comet was sitting at 15th magnitude. Bright enough for CCD imaging but too faint for nearly all visual observers. On April 20th Micheal Jager imaged the comet and found it too be much brighter. Over the next few days, visual observers were able to confirm the outburst and estimated the comet to be as bright as magnitude 8.9.

With perihelion in June, the comet is in full retreat from the Earth and Sun and has faded to 9th magnitude. The comet is slowly moving through western Virgo low in the western sky after evening twilight. This will be the last month to see the comet as it sinks into the twilight sky.

A finder chart for Comet Garradd can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Comet C/2008 T2 (Cardinal)

Rob Cardinal, an astronomer at the University of Calgary in Canada, discovered this comet last October. The comet was discovered as part of a survey at  the Rothney Astrophysical Observatory for new Near-Earth asteroids at high declinations. In fact the comet was found within 10 degrees of the North celestial pole. At the time of discovery, the comet was ~14th magnitude.

At perihelion on June 13th, the comet passed within 1.20 AU of the Sun. The comet can only be seen from the Southern Hemisphere as it is located south of the Sun. The comet is currently magnitude 9.0 to 10.0 as it moves southeast from Antilia to Vela and Centaurus in the evening sky. It is too bad the comet is located so far from Earth. At a distance of 1.8 AU from Earth, it is located on the other side of the Sun. If this comet has approached as close as Comet Lulin (0.4 AU) did, Comet Cardinal would be shining at 5th magnitude and be visible to the naked eye from dark locations.

A finder chart for Comet Cardinal can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

22P/Kopff

All of the above comets are long-period comets which will not return to the inner Solar System for thousands to millions of years. Comet Kopff is a frequent visitor with an orbital period of 6.4 years. Discovered on 1906 August 20 by August Kopff of Germany, the comet has been observed during every subsequent return except one.

The comet reached perihelion at 1.58 AU from the Sun on May 25. Though now moving away from the Sun, the comet still moving closer to Earth and will be located 0.78 AU from us at the end of the month. Recent observations place the comet at magnitude 9.5 which is about as bright as it will get this apparition. The comet spends August in Aquarius.

A finder chart for Comet Kopff can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Asteroids

Binocular and Small Telescope Asteroids (V < 10.0)

(3) Juno

Juno was the 3rd asteroid to be discovered after (1) Ceres and (2) Pallas. It was found by German astronomer Karl Harding on September 1, 1804. With dimensions of 320×267×200 km (192 x 160 x 120 miles) Juno ranks as the 10th largest asteroid in the Main Belt though it is the 2nd largest stony S-type asteroid.

This month it will be moving slowly eastward through Pisces while brightening from magnitude 9.0 to 8.2. Peak brightness will come at opposition on Sept. 22 when Juno will be as bright as magnitude 7.6. A few degrees to the eats of Juno is another bright asteroid, (18) Melpomene which is described in its own section.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Juno from Heavens Above.

(7) Iris

Iris is an inner Main-Belt asteroid that can occasionally get as bright as any asteroid. This year, Iris did not get as bright but still become a binocular object (albeit a difficult one) at opposition on July 4 at magnitude 8.7. During August, it is located in the constellation of Sagittarius at magnitude 9.3 at the start of the month and magnitude 9.8 at the end.

With a size of 240 x 200 x 200 km, Iris is the 5th largest stoney S-type asteroid. It was discovered in 1847 by John Russel Hind, the 1st of 10 asteroids he discovered.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Iris from Heavens Above.

(18) Melpomene

Just a few degrees to the east of (3) Juno lies another nice asteroid target for small telescopes. (18) Melpomene is also located in the constellation of Pisces and is only a little bit fainter than Juno, brightening from magnitude  9.4 to 8.7 in August.

Melpomene is another stoney S-type asteroid and similar to Iris was also discovered by John Russel Hind. Found in 1852, it is his 5th of 10 asteroid discoveries.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Iris from Heavens Above.

In The Sky This Month – June 2009

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of June 2009.

Note: If anyone has pictures or observations of these objects/events and want to share them, send me a comment. I’ll post them here.

Planets

Mercury - Mercury will be a morning object during June. Though it will be best placed for observation around the date of June 20, it will be visible for a week after that date. In fact, the planet will be slowly brightening during the time, so later dates may be easier for observing this elusive planet. Mercury can be seen very low in ENE sky right before dawn. It is better placed (higher in the sky) for southern hemisphere observers.

Saturn – Saturn is the easiest planet to observe in June. By the end of twilight, Saturn is high in the southwest under the eastern part of the constellation of Leo.

This year Saturn is dimmer than usual. At magnitude +0.9 to +1.0, there are at least a dozen or more stars that are brighter than it. The reason is the rings of Saturn contribute a lot  to the brightness of Saturn. But this year, is a ring plane crossing year meaning that the rings are nearly edge-on. As a result, the rings are reflecting much less light in the Earth’s direction this year. Saturn’s appearance through a telescope closely matches the below image taken on April 23. In June, the rings will be even closer to edge on then they were in the image below.

The Moon will pass a relatively distant 5.8 degrees to the south of Saturn on the evening of June 27.

Jupiter and Neptune - Jupiter rises in the middle of the night. Other than Venus, it is the brightest “star” at dawn with a  magnitude of -2.5 to -2.7. Due to Jupiter’s location in the southern constellation of Capricornus , it never gets very high this year.

For those with a telescope or binoculars and a dark sky, Neptune is located within 1/2 to 3/4 degrees of Jupiter. Jupiter will be a bright magnitude -2.5 to -2.7 while Neptune will be a faint +7.9. That makes Jupiter nearly ~12,000 times brighter than Neptune. Even Jupiter’s 4 large Galilean moons are about a dozen times brighter than Neptune even though they are much smaller. The big reason for the faintness of Neptune is its distance from both the Earth and Sun. It is roughly 6 times further away from us and the Sun as Jupiter. The distance also explains its apparent small size of 2.3″. A good sized telescope will be required to see Neptune as anything other than a faint star.

Though Neptune wasn’t discovered until 1846, it was actually observed by Galileo on two occasions in 1612 and 1613. Similar to this month’s circumstances, Jupiter was passing very close to Neptune. Galileo observed and recorded Neptune as a star in the vicinity of Jupiter. There is also evidence that he noticed that Neptune had moved but didn’t follow up on it. So when you observe these 2 planets imagine what Galileo must have been thinking nearly 400 years ago.

Uranus – Uranus is located in western Pisces. It is bright enough to be seen in small binoculars at magnitude +5.8 but will still require a telescope in order to see it as anything other than a star (it’s disk is only 3.5″ across).

Venus - Venus continues to slowly climb higher every night. It is currently a morning object and is best seen an hour before sunrise low in the eastern sky. For Southern Hemisphere observers, it is near its highest above the horizon for this apparition. For Northern observers, Venus will continue to climb higher until early August.

For binocular and telescope users, Venus will start the month as a “half moon”, 25″ across and 47% illuminated. By the end of the month, it will have shrunk to 19″ across but will also have a gibbous phase illuminated at 61%.

Mars – Mars can be seen very low in the eastern sky all month long. At magnitude +1.1, it is only as bright as some of the brighter stars. Mars and Venus are located within 5 degrees of each other all month. Closest approach will occur on June 21 when Mars will pass within 2 degrees of Venus. The two will steadily move apart for the rest of the year.

Meteors

The month of June experiences no major showers and only one minor one.  June is the last relatively low activity month before the “fireworks” of summer.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During June, 8 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

None

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors.

June Bootids (JBO)

The June Bootids are usually a very minor shower with very low rates, if any meteors,  seen in most years. On occasion the shower has put on good displays with as many as 50-100+ meteors per hour seen in 1998. Other years of enhanced activity include 1916, 1921, 1927 and 2004 when up to 30 meteors per hour were seen. The next predicted year for enhanced activity is next June in 2010. Though the shower is expected to be minor this year, the models aren’t perfect and anything can happen. Though active from June 22 to July 2, the peak night is June 27.

The parent of the June Bootids is the Jupiter family comet 7P/Pons-Winnecke. This comet was first seen by Jean-Louis Pons of Marsielles, France on 1819 June 12. Though it was recognized as a short period comet, a rarity at the time, it was lost until rediscovered by Friedrich Winnecke (Bonn, Germany) in 1858. Since then the comet has been observed at nearly every return including 3 returns when the comet passed exceptionally close to Earth (0.14 AU in 1921, 0.04 AU in 1927, and 0.11 AU in 1939). During the 1927 close approach the comet was bright enough to be an easy naked eye object. Since then the orbit of the comet has changed and moved further from the Sun and Earth. As a result, close approaches to Earth will not be possible until the comet’s orbit moves back closer to Earth’s around 2045.

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V = 6.0 – 8.0)

Comet C/2008 Q3 (Garradd)

This is the surprise comet of the summer. From time to time what appears to be a faint run-of-the-mill comet will undergo an outburst and brighten substantially. This is the case with Comet Garradd which was discovered by Gordon Garradd of the Siding Spring Survey (Australia). He used the 0.5-m Uppsala schmidt telescope to discover this comet back on 2008 August 27.

The comet was a faint 19th magnitude at discovery. With perihelion expected on 2009 June 23 at 1.80 AU from the Sun, it was expected to brighten but only to about 12th-14th magnitude. Two weeks ago the comet was sitting at 15th magnitude. Bright enough for CCD imaging but too faint for nearly all visual observers. On April 20th Micheal Jager imaged the comet and found it too be much brighter. Over the next few days, visual observers were able to confirm the outburst and estimated the comet to be as bright as magnitude 8.9.

Now more than a month after its outburst, the comet continues to brighten and has recently been estimated at magnitude 7.2. With perihelion this month, the comet should be as bright as it gets though one never knows with outburst comets.

At the start of the month, the comet is located in the far southern constellation of Circinus. As a result, it is only observable from the Southern Hemisphere. This quickly changes as the comet rockets to the north and becomes visible for most northern observers by mid-month. The comet travels from Circinus through Centaurus and Hydra before ending the month in Corvus.

A finder chart for Comet Garradd can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Small Telescope Comets (V = 8.0 – 10.0)

Comet C/2008 T2 (Cardinal)

Rob Cardinal, an astronomer at the University of Calgary in Canada, discovered this comet last October. The comet was discovered as part of a survey at  the Rothney Astrophysical Observatory for new Near-Earth asteroids at high declinations. In fact the comet was found within 10 degrees of the North celestial pole. At the time of discovery, the comet was ~14th magnitude.

At perihelion on June 13th, the comet will pass within 1.20 AU of the Sun. The comet is currently magnitude 8.5 as it moves south from Gemini into Canis Minor in the evening sky. For northern observers, this comet is getting hard to see and requires a clear and dark western horizon right after dusk. It is easier to see for southern observers where it will be located higher in the sky. After the first week or 2 of June, the comet will no longer be observable from the Northern Hemisphere.

A finder chart for Comet Cardinal can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Comet C/2006 W3 (Christensen)

This comet was discovered over 2 years ago on 2006 November 18 by Eric Christensen of the Catalina Sky Survey north of Tucson. At the time the comet was located at 8.7 AU from the Sun which is nearly the distance of Saturn. The comet continues to move closer to the Sun and Earth and is currently 3.8 AU from the Sun and 3.4 AU from the Earth.

The comet is currently around magnitude 8.8 and will slowly brighten during the month.  It is moving near the border of Lacerta and Pegasus.  The comet is best seen in the early morning.

The comet will reach perihelion at a still rather distant 3.12 AU from the Sun on 2009 July 6. At that time, the comet will be 8th magnitude and visible in many smaller backyard telescopes and even binoculars from dark sites. Christensen should remain bright enough to see in modest sized backyard telescopes for all of 2009.

On the morning of April 21, I was able to observe this comet with both 30×125 binoculars and a 12″ dobsonian. The comet was much easier to see in the 12″. Observation was made under a moderately light polluted sky with a limiting mag of ~+5.5.

A finder chart for Comet Christensen can be found at Comet Chasing and Aktuelle Kometen (in German).

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Comet C/2009 G1 (STEREO)

Jiangao Ruan of China found this comet on images taken by the SECCHI HI-1B instrument onboard one of the STEREO spacecraft. The comet was first visible on images taken on April 3 UT. Similar to SOHO (a spacecraft that was used to co-discover Comet C/2009 F6 (Yi-Swan)), the two STEREO spacecraft study the Sun and its immediate environment.

With perihelion on April 16 at 1.13 AU from the Sun, the comet is now moving away from the Sun. It is also moving away from the Earth and should slowly fade during the course of the month.

The comet starts the month the far southern constellation of Phoenix and will only travel further south reaching Pictor by month’s end . It was never an easy object for northern observers and is now only observable from southern latitudes.

A finder chart for Comet Christensen can be found at Comet Chasing and Aktuelle Kometen (in German).

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

22P/Kopff

All of the above comets are long-period comets which will not return to the inner Solar System in thousands to millions of years. Comet Kopff is a frequent visitor with an orbital period of 6.4 years. Discovered on 1906 August 20 by August Kopff of Germany, the comet has been observed during every subsequent return except one.

The comet reached perihelion at 1.58 AU from the Sun on May 25. Though now moving away from the Sun, the comet still moving closer to Earth and will be located 0.78 AU from us at the end of the month. Recent observations place the comet at magnitude 9.0 which is about as bright as it will get this apparition. The comet starts June in Capricornus north of Jupiter. For most of the month, Kopff is movng eastward through Aquarius.

A finder chart for Comet Kopff can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Asteroids

Binocular and Small Telescope Asteroids (V < 10.0)

(1) Ceres

Ceres is the biggest asteroid in the Main Belt with a diameter of 585 miles or 975 km. It is so big that it is now considered a Dwarf Planet. Classified as a carbonaceous (carbon-rich) Cg-type asteroid, there are suggestions that it may be rich in volatile material such as water. Some even propose that an ocean exists below its surface. Ceres is one of two targets for NASA’s Dawn spacecraft which is scheduled to visit it in 2015. This month Ceres fades from from magnitude 8.4 to 8.7 as it moves through eastern Leo in the evening sky. If you are observing Saturn with a telescope or pair of binoculars, try your hand at finding Ceres with one of the finder charts linked below.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Ceres from Heavens Above.

(7) Iris

Iris is an inner Main-Belt asteroid that can occassionally get as bright as any asteroid. This year, Iris will not get as bright but will still become a binocular object (albeit a difficult one) at opposition on July 4 at magnitude 8.7. During June, it is located in the constellation of Sagittarius at magnitude 9.7 at the start of the month and magnitude 8.8 at the end.

With a size of 240 x 200 x 200 km, Iris is the 5th largest stoney S-type asteroid. It was discovered in 1847 by John Russel Hind, the 1st of 10 asteroids he discovered.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Ceres from Heavens Above.

In The Sky This Month – May 2009

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of May 2009.

Note: If anyone has pictures or observations of these objects/events and want to share them, send me a comment. I’ll post them here.

Planets

Mercury - Last month saw Mercury’s best evening apparition of 2009 (at least for Northern Hemisphere observers). Mercury is now descending back into the glow of the Sun. For the first week or so of the month it is still visible low in the west during evening twilight. Unlike last month, it is much fainter now (+0.9 magnitude on the 1st, +3.7 on the 11th).

Saturn – Saturn is the easiest planet to observe in May. By the end of twilight, Saturn is just south of zenith (straight up) under the eastern part of the constellation of Leo.

This year Saturn is dimmer than usual. At magnitude +0.8 to +0.9, there are at least a dozen stars that are brighter than it. The reason is the rings of Saturn contribute a lot  to the brightness of Saturn. But this year, is a ring plane crossing year meaning that the rings are nearly edge-on. As a result, the rings are reflecting much less light in the Earth’s direction this year. Saturn’s appearance through a telescope will match the below image taken on April 23.

Image of Saturn by C. Hergenrother. April 23 w/ 12" with DMK41AF02 camera.

The Moon will pass a relatively distant 5.5 degrees to the south of Saturn on the evening of May 3.

Venus - Venus continues to slowly climb higher every night. It is currently a morning object and is best seen an hour before sunrise low in the eastern sky. For Southern Hemisphere observers, it will reach its highest point during the 2nd half of the month. For Northern observers, Venus will continue to climb higher until early August.

For binocular and telescope users, Venus will start the month as a large fat crescent, 39″ across and only 25% illuminated. By the end of the month, it will have shrunk to 25″ across but will also be nearly half illuminated at 46%.

Jupiter and Neptune - Jupiter rises a few hours before sunrise. By the end of the month, the king of the planets peaks above the horizon a little after midnight. Other than Venus, it is the brightest “star” in the morning sky at magnitude -2.2 to -2.4. Due to Jupiter’s location in the southern constellation of Capricornus , it never gets very high this year.

For those with a telescope or binoculars and a dark sky, Jupiter will pass close to the planet Neptune on the morning of May 27. At their closest, the 5th and 8th planet will only be 0.39 degrees apart. Jupiter will be a bright magnitude -2.4 while Neptune will be a faint +7.9. That makes Jupiter nearly ~12,000 times brighter than Neptune. Even Jupiter’s 4 large Galilean moons are about a dozen times brighter than Neptune even though they are much smaller. The big reason for the faintness of Neptune is its distance from both the Earth and Sun. It is roughly 6 times further away from us and the Sun as Jupiter. It’s distance also explains its apparent small size of 2.3″. A telescope will be required to see Neptune as anything other than a faint star.

Though Neptune wasn’t discovered until 1846, it was actually observed by Galileo on two occasions in 1612 and 1613. Similar to this month’s circumstances, Jupiter was passing very close to Neptune. Galileo observed and recorded Neptune as a star in the vicinity of Jupiter. There is also evidence that he noticed that Neptune had moved but didn’t follow up on it. So when you observe these 2 planets imagine what Galileo must have been thinking nearly 400 years ago.

Uranus – Uranus is located in western Pisces. It is bright enough to be seen in small binoculars at magnitude +5.9 but will still require a telescope in order to see it as anything other than a star (it’s disk is only 3.4″ across).

Both planets are early morning objects low in the southeastern sky.

Mars – Mars can be seen very low in the eastern sky all month long. At magnitude +1.2, it is only as bright as some of the brighter stars. Venus passed a distant 4 degrees to the north of Mars on April 24. Mars and Venus will continue to move apart until around mid-month when they will be 6.5 degrees apart. After that their distance from each other will shrink as they approach a 2 degree conjunction on June 21.

Meteors

The month of March experiences no major showers and only a few minor ones. It continues the annual lull in meteor activity from mid-January to mid-April.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During April, 8 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Eta Aquarids (ETA)

The Eta Aquarids are a major shower, especially for southern hemisphere observers, when they peak on May 5. For northern observers, the shower will only be observable for an hour or two before dawn. Since the radiant doesn’t get very high for NH observers, rates can be low. The radiant is located near the “jar” of Aquarius.

The ETA were produced by Comet Halley which also gives us the Orionids in October. Models suggest that the ETA were released by Comet Halley no later than 837 AD. The Orionids are easy to see because the particles are hitting the Earth from the anti-solar direction. This means the meteor shower can be seen in the middle of the night. The ETA are produced by meteoroids moving outbound from the Sun, as a result the radiant is located relatively close to the Sun. This means that the ETA radiant is only visible for an hour or so before twilight. By luck, the nearly Full Moon will have just set making the last hour of the night dark.

The shower spans from April 19 to May 28 with a peak around May 5 with a maximum ZHR of ~60.

Additional information on these showers and other minor showers not included here can be found at the following sites: Robert Lunsford’s Meteor Activity Outlook, Wayne Hally’s and Mark Davis’s NAMN Notes, and the International Meteor Organization’s 2008 Meteor Shower Calendar.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors.

Eta Lyrids (ELY)

This shower is associated with Comet C/1983 H1 (IRAS-Araki-Alcock). The comet is a long-period comet which passed within 0.03 AU of the Earth on 1983 May 11. Discovered by astronomers using the Infrared Astronomical Satellite (IRAS) and two amateur astronomers, Genichi Araki (Yuzawa, Niigata, Japan) and George Alcock (Peterborough, England, UK), the comet brightened to 1st magnitude for a few days around closest approach.

Though the comet is now long gone and will not return for quite some time, particles released during past perihelia can be observed every year in early May. The Eta Lyrids are a minor shower that have never produce more than ~3 meteors per hour. Peak time in on May 8 though some meteors can be seen from May 3-12. Meteors will appear to radiate from a point in the middle of a triangle made up of the bright stars Vega and Deneb and the “head” of the constellation Draco. The Moon, Full on May 7, will spoil the Eta Lyrids for this year.

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V < 8.0)

None

Small Telescope Comets (V < 10.0)

Comet C/2009 F6 (Yi-SWAN)

Comet C/2009 F6 (Yi-SWAN) is a long-period comet which will pass within 1.27 AU of the Sun on May 7. The comet is currently around magnitude 8.5 making it bright enough to be seen in small telescopes. Right now the nearly Full Moon will make observing the comet difficult but in a few days the Moon will not be a problem for evening observers. The comet is located northeast of the Sun. For southern hemisphere observers, you are out of luck. For northern observers, the comet can be observed in the evening sky.

The comet starts the month in Perseus. As it travels to the southeast, it will enter Auriga by the last week of the month. The comet will never get far from the horizon so a clear dark northwestern horizon is a must to see this comet. By mid-month the comet will be too close to the Sun for easy observation.

On the morning of April 21, I was able to observe Yi-SWAN with 30×125 binoculars. My observing location isn’t too dark with a limiting magnitude of ~+5.5. Even then, the summer Milky Way was faintly visible. The comet was barely visible as it was large and diffuse. Interestingly, the comet was not visible during multiple attempts to observe it during the evening hours. The darker morning sky most definitely helped. Unfortunately, in May the comet will not be visible in the morning.

The comet was found by Dae-am Yi of Yeongwol-kun, Gangwon-do, South Korea on March 26. He noticed the obvious blue-green glow of a comet on 2 images he took with a Canon 5D digital camera and a 90-mm f/2.8 lens. The other discoverer was Robert Matson of Irvine, CA. Mr. Matson found the comet on a series of images taken with the SWAN instrument on the SOHO (Solar Heliospheric Observatory) spacecraft starting on March 29.

A finder chart for Comet Yi-SWAN can be found at Comet Chasing and Aktuelle Kometen (in German).

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Comet C/2008 Q3 (Garradd)

Sometimes comets surprise us. From time to time what appears to be a faint run-of-the-mill comet will undergo an outburst and brighten substantially. This is the case with Comet Garradd. Gordon Garradd of the Siding Spring Survey (Australia) used the 0.5-m Uppsala schmidt telescope to discover this comet back on 2008 August 27.

The comet was a faint 19th magnitude at discovery. With perihelion expected on 2009 June 23 at 1.80 AU from the Sun, it was expected to brighten but only to about 12th-14th magnitude. Two weeks ago the comet was sitting at 15th magnitude. Bright enough for CCD imaging but too faint for nearly all visual observers. On April 20th Micheal Jager imaged the comet and found it too be much brighter. Over the next few days, visual observers were able to confirm the outburst and estimated the comet to be as bright as magnitude 8.9.

Whether the comet will continue in its excited state and brighten further as it approaches perihelion is not known. It’s possible that the outburst will be short-lived and the comet may revert back to its original activity level.

Right now this comet is only observable from the Southern Hemisphere as it rockets through the constellations of Indus, Pavo, Apus, Triangulum Australe, and Circinus. For us up north, the comet will become visible in June as an evening object.

I hope to have a link to a finder chart for this comet up soon.

Comet C/2006 W3 (Christensen)

This comet was discovered over 2 years ago on 2006 November 18 by Eric Christensen of the Catalina Sky Survey north of Tucson. At the time the comet was located at 8.7 AU from the Sun which is nearly the distance of Saturn. The comet continues to move closer to the Sun and Earth and is currently 3.8 AU from the Sun and 3.4 AU from the Earth.

The comet is currently around magnitude 9.5 and will slowly brighten during the month.  It is moving near the border of Lacerta and Pegasus.  The comet is best seen in the early morning.

The comet will continue to brighten as it approaches perihelion at a still rather distant 3.12 AU from the Sun on 2009 July 6. At that time, the comet will be 8th magnitude and visible in many smaller backyard telescopes and even binoculars from dark sites. Christensen should remain bright enough to see in modest sized backyard telescopes for all of 2009.

On the morning of April 21, I was able to observe this comet with both 30×125 binoculars and a 12″ dobsonian. The comet was much easier to see in the 12″. Observation was made under a moderately light polluted sky with a limiting mag of ~+5.5.

A finder chart for Comet Christensen can be found at Comet Chasing and Aktuelle Kometen (in German).

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Comet C/2009 G1 (STEREO)

Jiangao Ruan of China found this comet on images taken by the SECCHI HI-1B instrument onboard one of the STEREO spacecraft. The comet was first visible on images taken on April 3 UT. Similar to SOHO (a spacecraft that was used to co-discover Comet C/2009 F6 (Yi-Swan)), the two STEREO spacecraft study the Sun and its immediate environment.

With perihelion on April 16 at 1.13 AU from the Sun, the comet is now moving away from the Sun. Luckily it is still moving closer to the Earth, though it will get no closer than 1.06 AU from Earth. With a current estimated magnitude of ~9.0, the comet may brighten a bit as it gets closer.

The comet starts the month in southern Aquarius and will pass through Sculptor before finishing the month in the far southern constellation of Phoenix. It was never an easy object for northern observers and is now only observable from southern latitudes.

A finder chart for Comet STEREO can be found at Comet Chasing.

A nice collection of images can be found at Seiichi Yoshida’s Comet Homepage.

Comet C/2009 E1 (Itagaki)

This comet was found by amateur astronomer Koichi Itagaki of Yamagata, Japan on March 14. Comet C/2009 E1 (Itagaki) is a long-period comet which will come within 0.60 AU of the Sun at perihelion on April 7. It is also periodic in that it returns once every ~250 years according to the latest orbit.

This is the 1st comet to bear Koichi Itagaki’s name but it is not his 1st discovery. Back in 1968, he was a co-discoverer of Comet Tago-Honda-Yamamoto. Due to the rule that only the 1st 3 discoverers can have their name attached to a comet, his name was left off. Only a few months ago, he also re-discovered long-lost comet Giacobini.

The comet is located in the morning sky moving through Andromeda and to just north of the “square” of Pegasus. Due to its proximity to the Sun over the past few weeks, it hasn’t been observed since early April. At the time, it was magnitude 7.5-8.0. If it is still in the magnitude ~8.0 to 8.5 range then the  comet will bright enough to be seen in a reasonably sized backyard telescope.

A finder chart for Comet Itagaki can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany).

Comet C/2008 T2 (Cardinal)

Rob Cardinal, an astronomer at the University of Calgary in Canada, discovered this comet last October. The comet was discovered as part of a survey at  the Rothney Astrophysical Observatory for new Near-Earth asteroids at high declinations. In fact the comet was found within 10 degrees of the North celestial pole. At the time of discovery, the comet was ~14th magnitude.

At perihelion on June 13th of this year, the comet will pass within 1.20 AU of the Sun. The comet is currently ~9.0 to 9.5 magnitude as it moves south across Gemini into Canis Minor in the evening sky. The comet should continue to brighten by another magnitude this month. Similar to most comets, access to a clear western horizon is necessary to see it.

A finder chart for Comet Cardinal can be found at Comet Chasing and Aktuelle Kometen (in German).

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Asteroids

Binocular and Small Telescope Asteroids (V < 10.0)

(1) Ceres

Ceres is the biggest asteroid in the Main Belt with a diameter of 585 miles or 975 km. It is so big that it is now considered a Dwarf Planet. Classified as a carbonaceous (carbon-rich) Cg-type asteroid, there are suggestions that it may be rich in volatile material such as water. Some even propose that an ocean exists below its surface. Ceres is one of two targets for NASA’s Dawn spacecraft which is scheduled to visit it in 2015. This month Ceres fades from from magnitude 8.0 to 8.4 as it ends is retrograde motion just north of Leo. If you are observing Saturn with a telescope or pair of binoculars, try your hand at finding Ceres with one of the finder charts linked below.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Ceres from Heavens Above.

(8) Flora and (14) Irene

Irene was discovered by John Russel Hind in 1851, being only the 14th asteroid known at the time (if you are wondering ~400,000 asteroids have been discovered to date, we’ve come a long way). It is an S-type asteroid with a stoney or silicate composition. Its takes 6.3 years to orbit the Sun. This month Irene will fade from magnitude 9.0 to 9.7 as it moves through central Virgo.

Though it is a bit fainter than the asteroids I usually present, those up for a challenge can spot the asteroid (8) Flora a few degrees away from Irene.

Flora is a large asteroid roughly 136×136x113 km in dimension. It is innermost large asteroid in the Main Belt. As a result, it can get bright enough for backyard observers with modest sized telescopes and binoculars. Flora is a stoney S-type asteroid and also the largest member of the Flora family. This family was created when a large impact occured on Flora. The other family members are pieces of Flora that were thrown off by the impact.

Flora starts the month at magnitude 9.9. By the end of the month, it has faded to 10.5. Flora and Irene provide us with a 2-for since both objects are located within 5 degrees of each other.

Since I have not been able to find a nice star chart showing the position of Irene and Flora, here is one I made with the C2A program. The bright star that Flora passes close to towards the end of the month (right side of the chart, white circle) is zeta Virginis.

Another New Comet – C/2009 G1 (STEREO)

Yet another relatively bright comet has been discovered. Jiangao Ruan of China found the 10th magnitude comet on images taken by the SECCHI HI-1B instrument onboard one of the STEREO spacecraft. The comet was first visible on images taken on April 3 UT. Similar to SOHO (a spacecraft that was used to co-discover Comet C/2009 F6 (Yi-Swan)), the two STEREO spacecraft study the Sun and its immediate environment. Since the comet was found in spacecraft data it is named after the spacecraft, in this case, STEREO. This spacecraft based naming scheme is also used for comets found with the SOHO coronographs (named Comet SOHO) and the SOHO SWAN lyman-alpha imager (named Comet SWAN). The spacecraft data being used for comet discovery is in the public domain and many of the discoverers are amateur astronomers analysing the data on their computers.

This is Mr. Ruan’s 19th comet discovery with all of the his comets being found in data from the SOHO and STEREO spacecraft. All 19 comets have been discovered in the past 11 months. As impressive as that number is, the SOHO spacecraft has been used to find ~1600 comets since 1996. Most of these comets are very faint and are only bright enough to be observed when extremely close to the Sun. Unfortunately, the only place one can observe objects that faint and that close to the Sun is above the Earth’s atmosphere. Some more info on the discovery and movies of the discovery images can be found at the Naval Research Lab’s Sungrazing Comet page.

C/2009 G1 (STEREO) is different from the usual SOHO and STEREO comet. Instead of a small faint comet that only gets bright enough to see because it comes within a few solar radii of the Sun, Comet STEREO is a nice sized comet orbiting the Sun at nearly the same distance as the Earth. With perihelion on April 16 at 1.13 AU from the Sun, the comet is as close to the Sun as it will get. Luckily it will get closer to the Earth over the next 2 months, though it will get no closer than 1.06 AU from Earth. With a current estimated magnitude of ~10.5, the comet may brighten a bit as it gets closer.

Orbit of Comet C/2009 G1 (STEREO). Position of the comet and planets valid for April 15. Produced with C2A.

The comet is located low in the southeastern sky right before the start of dawn. Moving through Aquarius the comet is much easier to see from the southern hemisphere. The comet’s orbit with an inclination of 108 degrees is carrying it further to the south. It will never be an easy object for northern observers. In fact, within a month it will only be observable from the southern latitudes.

Finder chart for Comet STEREO for April 10 to May 1 UT. The chart was created with the C2A program.

New Comet – C/2009 F6 (Yi-SWAN)

A new comet has been discovered that should be the brightest comet in the sky this month. Comet C/2009 F6 (Yi-SWAN) is a long-period comet which will pass within 1.27 AU of the Sun on May 7. The comet is currently around magnitude 8.5 making it bright enough to be seen in small telescopes. Right now the nearly Full Moon will make observing the comet difficult but in a few days the Moon will not be a problem for evening observers. The comet is located north of the Sun. For southern hemisphere observers, you are out of luck. For northern observers, the comet can be observed in both the evening and morning sky.

The below orbit diagram shows the position of the comet at perihelion. Note the high inclination (angle between the orbit of Earth and the comet) of 85 degrees. As a result, the comet is orbiting almost perpendicular to the orbit of the planets. Unfortunately, the comet is rather far from Earth. It has already come as close to Earth as it can at ~1.8 AU and will slowly move away with time.

Orbit of Comet C/2009 F6 (Yi-SWAN). Position of the comet and planets valid for May 5. Produced with C2A.

Currently the comet is located in Cassiopeia. It is moving to the east and will enter Perseus by mid-month. The comet should continue to brighten as it approaches perihelion and may be as bright as magnitude 8.0.

Finder chart for Comet Yi-SWAN for April 10 to May 1 UT. Note the dates lie directly to the right of the corresponding position. The chart was created with the C2A program.

The comet was found by Dae-am Yi of Yeongwol-kun, Gangwon-do, South Korea on March 26. He noticed the obvious blue-green glow of a comet on 2 images he took with a Canon 5D digital camera and a 90-mm f/2.8 lens. According to a post on the MPML mailing list by Maik Meyer, this is the 1st comet discovered by and named for a Korean citizen in the modern age. There were first sightings of comet by Koreans in the 18th century before the comets were named for their discoverers.

The other discoverer was Robert Matson of Irvine, CA. Mr. Matson found the comet on a series of images taken with the SWAN instrument on the SOHO (Solar Heliospheric Observatory) spacecraft starting on March 29. The SWAN insturment images the entire sky for solar Lyman-alpha particles that are backscattered off of neutral hydrogen atoms. In this way, SWAN can monitor the activity of the far-side of the Sun. This instrument is also excellent at detecting the glow of hydrogan in the extended coma of comets.

In The Sky This Month – 2009 April

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of April 2009. The month sees the return of the borderline major meteor shower, the Lyrids. The highlight of the month is the lunar occultation of Venus right before dawn on April 22.

Note: If anyone has pictures or observations of these objects/events and want to share them, send me a comment. I’ll post them here.

Planets

Mercury - This month brings us the best opportunity of the year to observe Mercury in the evening sky (for Northern Hemisphere observers). Mercury will be at its highest on April 26, though even then it will be low in the western sky 30-60 minutes after sunset.

The Moon will also located just above Mercury on the evening of April 26. The image below shows what the scene will look like from North America. Note that the Pleiades open star cluster will be located between Mercury and the Moon. It will be a great sight via your eye or binoculars. In a telescope, Mercury will appear as a fat crescent with ~36% of its disk illuminated.

Map of the Moon-Mercury-Pleiades conjunction on the evening of April 26. Map made with Stellarium.

Saturn – Saturn is the only planet visible in the evening sky. By the end of twilight, Saturn is high in the southeast under the eastern part of the constellation of Leo.

This year Saturn is dimmer than usual. At magnitude +0.6 to +0.7, there are at least 11 stars that are brighter than it. The reason is that the rings of Saturn contribute a lot  to the brightness of Saturn. But this year, is a ring plane crossing year meaning that the rings are nearly edge-on. As a result, the rings are reflecting much less light in the Earth’s direction this year. Saturn’s appearance through a telescope will match the below image taken by Bob Lunsford on March 28. Note the small dark spot near the top edge of Saturn’s disk, this is a shadow cast by Saturn’s largest moon, Titan.

Image of Saturn by Bob Lunsford from 2009 March 28. Titan's shadow seen near top.

The Moon will pass a relatively distant 5.5 degrees to the south of Saturn on the evening of April 6.

Venus - After spending the past few months dominating the evening sky, Venus will now spend the rest of the year as a morning object. If you live south of the Equator, Venus will appear to rocket higher and higher every morning. In fact it should be an easy sight by the 2nd week of April if you have a clear eastern horizon. Venus will reach its highest in late May.

For those of us north of the Equator, Venus will take a little longer to gain altitude. Though it is already visible for observers with a clear eastern horizon, Venus will slowly climb higher every night. For  northern observers, Venus won’t reach its highest till August. Regardless of where you are observing, Venus will be at its brightest on April 29 though it is always a very bright object.

For binocular and telescope users, Venus will start the month as a large thin crescent, 59″ across and only ~2% illuminated. By mid-month, it will have shrunk to ~50″ across but it will also become a fatter crescent with ~12% of the disk illuminated. By the end of the month, it is 39″ across and 25% illuminated

Venus is also involved in the coolest event of the month. On the morning of April 22, the Moon will occult (or pass in front) of Venus for observers in most of North America. The below map from the International Occultation Timing Association (IOTA) shows where the occultation will be visible. Times for the beginning and end of the occultation can be found at IOTA’s site. I’ll write more about this as the date draws closer.

The following diagram gives a good representation of what the occultation will look like right before the Moon passes in front of Venus on the morning of April 22. Note that Mars will be located nearby as well. For those with binoculars or a telescope, Venus will appear as a thin crescent similar to, but much smaller than, the Moon.

The Moon, Venus and Mars just before the start of the occulatation of Venus on the morning of April 22. Sky map produced with Stellarium.

Jupiter - Jupiter rises a few hours before sunrise. Other than Venus, it is the brightest “star” in the morning sky at magnitude -2.2. Due to Jupiter’s location in the southern constellation of Capricornus , it never gets very high this year.

Mars – Mars can be seen very low in the eastern sky all month long. At magnitude +1.2, it is only as bright as some of the brighter stars. Venus will pass a distant 5.5 degrees to the north of Mars on April 24. As a result, Mars will be located just below the spectacular Moon-Venus occultation.

Meteors

The month of March experiences no major showers and only a few minor ones. It continues the annual lull in meteor activity from mid-January to mid-April.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During April, 8 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Lyrids (LYR)

April brings the first major meteor shower since the Quadrantids in early January. The Lyrids are produced by Comet Thatcher, a comet on a ~400 years orbit that has only been observed in 1861. The Lyrids, on the other hand, can be seen every year.

The radiant is located between the constellations of Lyra and Hercules. Though the radiant rises during the evening, the best time to see Lyrids is after 11 pm when the radiant is high in the sky.

The shower is active from April 16 to 25 with a peak on the morning of April 22. The shower only shows good levels of activity on the night of the peak. Even then, this is the most minor of the major showers with a peak rate of ~15-25 meteors per hour.

Though there are no predictions on enhanced activity, the Lyrids have been known to put on grand displays. The 1st great display goes back almost 25oo years while the last happened in 1982. So you never know, this year could be the next good display.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors.

Pi Puppids (PPI)

The Pi Puppids are usually a very low activity shower. In 1977 and 1982, the shower put on a good display with up to 60 meteors per hour being observed. This shower radiates from the far southern constellation of Puppis and can not be seen from most of North America and Europe.

We now know that the Pi Puppids are created by Comet 26P/Grigg-Skjellerup. P/G-S is a small Jupiter family comet that orbits the Sun once every 5.3 years.

There are no predictions for enhanced material this year. The shower is active from April 15-28 with a peak on April 23. At its best we should expect 1-2 meteors per hour with even that number being optimistic for northern observers.

Eta Aquarids (ETA)

The Eta Aquarids are a major shower, especially for southern hemisphere observers, when they peak on May 5. During the month of April, the shower can be considered a minor shower.

The ETA were produced by Comet Halley which also gives us the Orionids in October. Models suggest that the ETA were released by Comet Halley no later than 837 AD. The Orionids are easy to see because the particles are hitting the Earth from the anti-solar direction. This means the meteor shower can be seen in the middle of the night. The ETA are produced by meteoroids moving outbound from the Sun, as a result the radiant is located relatively close to the Sun. This means that the ETA radiant is only visible for an hour or so before twilight.

The shower spans from April 19 to May 28 with a peak around May 5 with a maximum ZHR of ~60. The last week of April will see some low activity (ZHR < 10) from the ETAs.

Additional information on these showers and other minor showers not included here can be found at the following sites: Robert Lunsford’s Meteor Activity Outlook, Wayne Hally’s and Mark Davis’s NAMN Notes, and the International Meteor Organization’s 2008 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V < 8.0)

None

Small Telescope Comets (V < 10.0)

Comet C/2009 E1 (Itagaki)

This recently discovered comet was found by amateur astronomer Koichi Itagaki of Yamagata, Japan. Comet C/2009 E1 (Itagaki) is a long-period comet which will come within 0.60 AU of the Sun at perihelion on April 7. It is also periodic in that it returns once every ~250 years according to the latest orbit.

This is the 1st comet to bear Koichi Itagaki’s name but it is not his 1st discovery. Back in 1968, he was a co-discoverer of Comet Tago-Honda-Yamamoto. Due to the rule that only the 1st 3 discoverers can have their name attached to a comet, his name was left off. Only a few months ago, he also re-discovered long-lost comet Giacobini.

The comet is located in the evening sky north of the constellation of Aries. As the month progresses the comet will move north of the Sun as it travels through Triangulum, northern Pisces and Andromeda. Only observers with a clear view of the northwestern horizon in the evening and northeastern horizon in the morning will be able to see the comet. By May the comet will only be visible in the morning sky and will be much easier to see.

At magnitude ~8.0 to 8.5, the comet is bright enough to be seen in a reasonably sized backyard telescope. Having said that, I was just barely able to see it from my backyard in Tucson with my 12″ telescope due to the city lights and the bright twilight.

A finder chart for Comet Itagaki can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany).

Comet C/2009 F6 (Yi-SWAN)

A new comet has been discovered that should be the brightest comet in the sky this month. Comet C/2009 F6 (Yi-SWAN) is a long-period comet which will pass within 1.27 AU of the Sun on May 8. The comet is currently around magnitude 8.5 making it bright enough to be seen in small telescopes. Right now the nearly Full Moon will make observing the comet difficult but in a few days the Moon will not be a problem for evening observers. The comet is located north of the Sun. For southern hemisphere observers, you are out of luck. For northern observers, the comet can be observed in both the evening and morning sky.

Currently the comet is located in Cassiopeia. It is moving to the east and will enter Perseus by mid-month. The comet should continue to brighten as it approaches perihelion and may be as bright as magnitude 8.0.

On the morning of April 21, I was able to observe Yi-SWAN with 30×125 binoculars. My observing location isn’t too dark with a limiting magnitude of ~+5.5. Even then, the summer Milky Way was faintly visible. The comet was barely visible as it was large and diffuse. Interestingly, the comet was not visible during multiple attempts to observe it during the evening hours. The darker morning sky most definitely helped.

The comet was found by Dae-am Yi of Yeongwol-kun, Gangwon-do, South Korea on March 26. He noticed the obvious blue-green glow of a comet on 2 images he took with a Canon 5D digital camera and a 90-mm f/2.8 lens. The other discoverer was Robert Matson of Irvine, CA. Mr. Matson found the comet on a series of images taken with the SWAN instrument on the SOHO (Solar Heliospheric Observatory) spacecraft starting on March 29. The SWAN insturment images the entire sky for solar Lyman-alpha particles that are backscattered off of neutral hydrogen atoms. In this way, SWAN can monitor the activity of the far-side of the Sun. This instrument is also excellent at detecting the glow of hydrogan in the extended coma of comets.

Comet C/2007 N3 (Lulin)

Comet Lulin was discovered by the Lulin Sky Survey in Taiwan on 2007 July 11. At the time the comet was located beyond the orbit of Jupiter. The comet will be closest to the Sun on 2009 January 10 at 1.21 AU from the Sun. It will be closest to Earth in late-February when it will be only 0.41 AU from us.

The comet is fading after its closest approach to Earth in late February. It is a evening object and spends all of April moving westward through western Gemini. The comet starts the month around magnitude 8.5 and should fade to magnitude 10.0 or fainter by the end of the month.

A finder chart for Comet Lulin can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Comet C/2006 W3 (Christensen)

This comet was discovered over 2 years ago on 2006 November 18 by Eric Christensen of the Catalina Sky Survey north of Tucson. At the time the comet was located at 8.7 AU from the Sun which is nearly the distance of Saturn. The comet continues to move closer to the Sun and Earth and is currently 3.8 AU from the Sun and 3.4 AU from the Earth.

The comet is currently around magnitude 9.5 and will slowly brighten during the month.  It is moving near the border of Lacerta and Pegasus.  The comet is best seen in the early morning. I was able to observe the comet visually with my backyard 12″ reflecting telescope back in November. Being small and condensed, the comet was fairly easy to see.

The comet will continue to brighten as it approaches perihelion at a still rather distant 3.12 AU from the Sun on 2009 July 6. At that time, the comet will be 8th magnitude and visible in many smaller backyard telescopes and even binoculars from dark sites. Christensen should remain bright enough to see in modest sized backyard telescopes for all of 2009.

On the morning of April 21, I was able to observe this comet with both 30×125 binoculars and a 12″ dobsonian. The comet was much easier to see in the 12″. Observation was made under a moderately light polluted sky with a limiting mag of ~+5.5.

A finder chart for Comet Christensen can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Asteroids

Binocular and Small Telescope Asteroids (V < 10.0)

(1) Ceres

Ceres is the biggest asteroid in the Main Belt with a diameter of 585 miles or 975 km. It is so big that it is now considered a Dwarf Planet. Classified as a carbonaceous (carbon-rich) Cg-type asteroid, there are suggestions that it may be rich in volatile material such as water. Some even propose that an ocean exists below its surface. Ceres is one of two targets for NASA’s Dawn spacecraft which is scheduled to visit it in 2015. Last month Ceres was at opposition (at its closest to the Earth and at its brightest). This month Ceres will fade from from magnitude 7.4 to 8.0 as it ends is retrograde motion just north of Leo. If you are observing Saturn with a telescope or pair of binoculars, try your hand at finding Ceres with one of the finder charts linked below.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Ceres from Heavens Above.

(2) Pallas

Pallas is also a carbonaceous asteroid though with a slightly bluish B-type spectrum. Due to its high inclination (tilt of its orbit with respect to Earth’s orbit) of 34 degrees it is a difficult target for future spacecraft missions. Pallas is large with dimensions of 350×334x301 miles or 582×556x501 km. This month it continues moving north, leaving the constellation of Orion and entering Monoceros. It fades from  magnitude 8.7 to 8.9 over the course of the month.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Pallas from Heavens Above.

(8) Flora

Flora is a large asteroid roughly 136×136x113 km in dimension. It is innermost large asteroid in the Main Belt. As a result, it can get bright enough for backyard observers with modest sized telescopes and binoculars. Flora is a stoney S-type asteroid and also the largest member of the Flora family. This family was created when a large impact occured on Flora. The other family members are pieces of Flora that were thrown off by the impact.

Flora starts the month at magnitude 10.0. It reaches its maximum brightness on April 22 at magnitude 9.8. By the end of the month, it has slightly faded to 9.9. Flora and Irene provide us with a 2-for since both objects are located within 5 degrees of each other.

Since there I have not been able to find a nice star chart showing the position of Flora, here is one I made with the C2A program. It also shows the position of Irene.

(14) Irene

Irene was discovered by John Russel Hind in 1851, being only the 14th asteroid known at the time (if you are wondering ~400,000 asteroids have been discovered to date, we’ve come a long way). It is an S-type asteroid with a stoney or silicate composition. Its takes 6.3 years to orbit the Sun.

This month Irene will brighten from magnitude 9.2 to a maximum of 8.9 on April 24 as it retrogrades through western Virgo. Remember Flora is located within 5 degrees of Irene.

(15) Eunomia

Discovered in 1851, Eunomia is one of the largest stoney S-type asteroids. Its dimensions are roughly 357×255×212 km. Similar to Flora, Eunomia is also the parent body of its own family.

Eunomia spends all of April in the constellation of Corvus, just to the south of Virgo. With opposition on April 2, the asteroid is as bright as it’s going to get this year at magnitude 9.8. As the month progresses it will fade to 10.0. This year Eunomia is at aphelion, its furthest from the Sun making this one of its faintest oppositions. When at perihelion, it can get as bright as magnitude ~8.

Since there I have not been able to find a nice star chart showing the position of Eunomia, here is one I made with the C2A program.

(29) Amphitrite

Discovered in 1854, Amphitrite was the 29th asteroid to be discovered. Similar to Euterpe, Amphitrite is also a stoney S-type asteroid. With an average diameter of  127 miles (212 km) it is bigger than Euterpe though its further distance from the Earth and Sun keeps it from getting as bright.

Amphitrite fades from magnitude 9.5 to 10.1 this month. It spends the entire month in eastern Virgo not far from Saturn. If you are observing Saturn, take a short star-hopping trip to Amphitrite

Since there I have not been able to find a nice star chart showing the position of Amphitrie, here is one I made with the C2A program.