In the Sky This Month – December 2009

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of December 2009. Jupiter continues its reign as not only king of the planets but king of the evening sky. Though not visible until about 10pm or so, Mars will start to contest Jupiter’s reign this month. December also brings the Geminids which are one of the best meteor showers of the 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

Mercury - Mercury will be an evening object this month. Though not a great apparition for northern observers, it should be easy to see if you have an unobstructed view of the southwestern horizon. The best time to see Mercury will be when the Moon passes near it on during the evenings of Dec 17 and 18. At that time Mercury will be magnitude -0.5. By the end of the month, it will be rapidly fading and getting closer to the Sun.

Dec 18 - Moon within 1.3° of Mercury

Jupiter - Jupiter continues to dominate the early evening sky. At magnitude -2.2, 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 southwestern 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.

Dec 21 - Moon passes 4° from Jupiter
Dec 21 - Jupiter passes 0.5° from Neptune

Neptune – For those with a telescope or binoculars and a dark sky, Neptune is located within a few degrees of Jupiter. This month Jupiter and Neptune will experience the 3rd of this year’s triple conjunction as they pass ~0.5° from each other on the night of Dec 20/21. For most of the month, the 2 planets will be very close to each other and within the same field of view of most small telescopes and binoculars. This is a great opportunity to use the easy-to-find Jupiter to help locate the usually hard-to-find Neptune. Jupiter will be a bright magnitude -2.2 while Neptune will be a faint +8.0. 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.

Dec 21 - Jupiter passes 0.5° from Neptune

Uranus – Uranus is located in western Pisces and 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 3.5″ across).

Mars – Mars can be seen rising in the eastern sky late in the evening (~9:30 pm at the start of the month and ~8 pm at the end of the month). Mars is rapidly brightening and will double in brightness this month as it rises from +0.0 to -0.7 magnitude. By the end of the month, Mars will be brighter than all stars expect Sirius and far southern Canopus. Mars will continue to brighten to a max of magnitude -1.3 at its opposition on Jan 29 of next year. This month Mars will appear roughly stationary as it starts its retrograde motion near the Leo/Cancer border.

Dec 6 - Moon passes close (5°) to Mars

Saturn – Saturn is easy to observe during the last few hours of the night. Located in Virgo at magnitude +0.9, Virgo only rises right before the start of dawn. Telescope users should note that Saturn’s rings are still close to edge-on.

Dec 10 - Moon and Saturn within 7° of each other

Venus - Venus will be too close to the Sun this month for most observers. Some with unobstructed views of the southeastern horizon may catch a glimpse of Venus rising 30-50 minutes or so before sunrise.

Dec 15 - Venus and Moon within 3° of each other

Meteors

December hosts one of the best showers of the year in the Geminids. In addition, the background rate of meteors is still rather 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 December, 10 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Geminids (GEM)

Along with the Perseids of August, the Geminids are one of the best meteor showers delivering great displays year after year. This year’s Geminids are perfectly timed as the Moon will be nearly New and will not spoil the show.

According to Sirko Molau’s analysis of video data, the Geminids are already observable at the beginning of the month though their rates are very low. The peak is predicted for the night of December 13/14 though numerous meteors should be visible for a day or two on either side of the peak. With a radiant near the star Castor in the constellation of Gemini, the Geminids are one of the rare major showers that are observable before midnight and can be observed as early as 8:00 pm though rates are usually best after 10:00 pm. Under a dark rural moon-less sky, the Geminids can produce as many as 100+ meteors per hour. Observers under suburban skies will see lower rates.

The Geminids are the result of the break-up and subsequent activity of the “asteroid” Phaethon. Why asteroid in quotes? Most meteor showers come from comets yet Phaethon is on a very non-cometary orbit and has never shown any cometary activity. There is still much scientific discussion about what exactly Phaethon is.

More details on the Geminids and their parent “asteroid” Phaethon will be posted as we get closer to its peak.

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.

Ursids (URS)

The Ursids will produce up to 10 meteors per hour at their peak on December 22-23. That rate makes it a borderline major/minor shower though the Ursids have experienced a number of outbursts in the past. With a radiant near the “bowl” of Ursa Minor (the “Little Dipper”), this shower is also observable all night long though the best time to observe it is during the last hours of the night.

Additional information on these showers and other minor showers not included here can be found at the following sites: 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 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 in the early morning hours as a ~9.0 to 9.5 magnitude comet in Coma Berenices. At mid-month the comet is 2.38 AU from the Sun and 2.43 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.

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 fainter (95 mag or fainter) this month. The comet is located low in the southwest sky after dusk and will spend the monthcrossing Capricornus. At mid-month P/Howell will be 1.53 AU from the Sun and 2.02 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.

Asteroids

Binocular and Small Telescope Asteroids (V < 9.0)

(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 7.7 to 7.2 as it travels 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.

In The Sky This Month – October 2009

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of October 2009. Jupiter continues its reign as not only king of the planets but king of the evening sky. October also brings the Orionids, one of the year’s better meteor showers.

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 -2.6, Jupiter is ~11 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.

Oct 27 - Moon passes 3° from Jupiter

View of the evening sky around 8pm on Oct 16. Sky chart made with Stellarium planetarium software.

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 -2.6 while Neptune will be a faint +7.9. That makes Jupiter over ~16,000 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 a month past opposition and still near its maximum in brightness. 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).

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. Mars is rapidly brightening from magnitude +0.9 to +0.6, its brightness 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 Gemini into Cancer. By Halloween, the planet will be moving through the Beehive,  a big bright star cluster in Cancer.

Oct 12 – Moon within 1.1° of 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. 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).

Oct 13 – Saturn and Venus within 0.5° of each other
Oct 16 – Moon passes 6° from Venus

Mercury - Mercury puts on its best morning show of the year for northern observers. Below the equator, this is one of Mercury’s worst displays and probably worth skipping. For the 1st 3 weeks of the month, Mercury will be visible about 30 minutes before the start of dawn in the evening sky. The dates below highlight some of the best mornings to observe Mercury.

Oct 6 – Mercury furthest above eastern horizon at dawn
Oct 8 – Saturn and Mercury within 0.3° of each
Oct 17 – Moon and Mercury within 7° of each other

Saturn – After spending the last month or so too close to the Sun to be seen, Saturn is once again visible. Located in Virgo at magnitude +1.0, Virgo only rises right before the start of dawn. For those of you lucky enough to be up every morning and have access to a clear eastern horizon, October will provide a month long show as Venus, Mercury and Saturn dance among themselves. Telescope users should note that Saturn’s rings are still close to edge-on.

Oct 8 – Saturn and Mercury within 0.3° of each
Oct 13 – Saturn and Venus within 0.5° of each other
Oct 16 – Moon and Saturn within 6° of each other

Meteors

October hosts one of the best meteor showers of the year in the Orionids. 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 September, 12 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Orionids (ORI) [Max Date = Oct 22, Max Rate = ~20-70 per hour]

The Orionids are one of the most reliable and productive showers of the year. Another point in their favor, is there high level of activity over the course of about 5 nights. This gives ample opportunity to catch a few ORI meteors.

The meteors that make up the Orionid shower were originally released by the one comet everyone has heard of, Comet Halley. Computer simulations of the past movements of Halley and its dust suggest that many of this year’s Orionid meteors were released by Halley between 1265 BC and 910 BC (for some points of reference, the Trojan War took place around 1200 BC and King David ruled around 1000 BC).

The Orionids are usually active from Oct 3 to Nov 11 with a broad peak between Oct 18 and 24. During their peak, rates can be as high as 20-70 meteors per hour. Last year rates reached 39 meteors per hour which is nearly half the rate observed in 2007 (70 per hour). With no Moon in the sky, the sky will be nice and dark this year.

The Orionids appear to come from an area in northern Orion. This area, called the radiant, rises around 10pm local time. It is best to wait till the radiant is high in the sky before looking for meteors (say 1am). The radiant is highest around 3:30am which is the best time to look. As you can see on the sky chart, the Moon is almost on top of the radiant. Meteors can appear anywhere in the sky so you don’t have to look at the radiant.

More can be found at an earlier Orionid posting.

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.

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 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 3.3 AU from the Sun and 3.2 AU from Earth. Though observed as bright as magnitude ~8.2 it is now around magnitude 8.8.  It is moving southeast while paralleling the summer Milky Way. This month the comet can be found in southern Aquila and is well placed for evening observing.

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 88P/Howell

P/Howell is another evening comet and should be just as bright as C/Christensen. 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 a 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.

This year the perihelion occurs on Oct 12 when it will shine at ~9.0 magnitude or maybe even a little brighter. The comet is located low in the southwest sky after dusk where it will start the month in the constellation of Scorpius before traversing Ophiuchus and ending the month in Sagittarius. At mid-month P/Howell will be 1.36 AU from the Sun and 1.65 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 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 non-descript smudge about 1.5′ across and with a brightness of magnitude 10.1.

This month the comet will be visible in the morning sky moving from southern Orion into the faint Milky Way constellation of Monoceros. It should remain at magnitude ~10 for the entire month.

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)

After 2 short-period comets, this next comet is of the long-period variety. Comet C/2007 Q3 (Siding Spring) was first seen on 2007 August 25 by Donna Barton of the Siding Spring Survey in Australia. This Oct. 7 the comet will reach its rather distant perihelion at 2.25 AU from the Sun. Unfortunately, the comet and Earth are located on opposite sides of the Sun (a 3.0 AU distance). Still the comet may be observable during the 2nd half of the month right before the start of dawn as a ~9.5 to 10.0 magnitude comet in Leo.

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 October it will fade from magnitude 7.8 to 8.4. 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, peaking at magnitude 7.9 on Oct 10 and fading to magnitude  7.9 by month’s end.

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.

Saturn and Venus

The evening sky is graced by two planets, brilliant Venus low in the western sky and Saturn in the eastern sky. As nice as these planets look to the eye, telescopes can reveal even more about these worlds.

Saturn has 61 satellites (moons) with good orbits. It undoubtedly has many more and if we count every particle in its rings the count would probably be in the millions. Most of the 61 known satellites are very small (a few miles in diameter) and only observable in large telescopes or by the Cassini spacecraft that is currently orbiting Saturn.

Luckily a few satellites are observable in small backyard telescopes. Titan, the 2nd largest satellite in the solar system, is even visible in binoculars. Through my backyard 12″ telescope I can usually see 6 satellites. Imaging can pick up a few more. Images from the night of March 15/16 found 7 satellites in the close vicinity of Saturn.

The below image is a combination of two different exposure times, very short exposures to see the rings and cloud bands of Saturn and longer exposures to detect the moons. The detected moons include Enceladus, Tethys, Dione, Rhea, Titan, Hyperion and Iapetus.

Venus continues to drop closer to the Sun every evening. As it comes closer to Earth and moves between the Sun and Earth, Venus is becoming larger and more narrow. The below collage documents the apparent changes in our view of Venus over the past 9 days.

A more dramatic display of the changes over the past 9 days can be seen when images from March 8 and 17 are placed next to each other. The camera and telescope used is the same for each night. The magnification used is also the same. The change in size and thickness of the crescent is due to Venus moving closer to Earth.

The Past Week in Pictures

Yet another night of thick clouds here in Arizona. I wouldn’t mind if it would actually rain. Not only are the clouds shutting down the meteor survey being conducted by myself and Bob Lunsford but also the professional Near-Earth asteroid surveys located nearby.

While we wait for the sky to clear, here are a few nice images from the past week.

Photographer John Rav took a great picture of Venus setting behind Agathla (also called El Capitan), a volcanic plug in Monument Valley, Arizona. The photo is a ~15 minute time-lapsed photo so Venus and the stars are trailed as they move across the sky. Venus is the brightest star in the middle of the picture. Also note the Square of Pegasus to the right of Agathla and Diphda (the brightest star in Cetus the whale) at the far left. More images by John can be found at his Flickr site. Thanks for sharing your photos, John!

The next 2 planetary images were taken with my 12″ Dobsonian telescope on the evening of February 26. The camera used was a DMK 41AF02.AS by ImagingSource. Recently I purchased a tracking mount which allows me to image objects for more than a fraction of a second. Each planetary image below is actually a combination of 100-200 very short exposures (usually less than 0.1 seconds).  The images are close to what the view of Venus and Saturn would be like in a small backyard telescope.

The next image was taken with the same planetary video camera as the Venus and Saturn images above. But, instead of observing through a telescope I used a small wide-field lens (Computar 4mm f/1.2). This is the same type of lens I use for my meteor observations.

The comet is the slightly elongated fuzz below Regulus. It is more obvious in the 2x magnified view in the bottom right. It is interesting to note that the largest Main Belt asteroid (and now dwarf planet) Ceres is also visible in the image. I wasn’t aware of this until after the image was taken. So it was a nice surprise. I haven’t looked at Ceres through a telescope since 1992-93. It’s probably time to pay it a visit once again.

I have recently purchased a larger lens, the Computar 12mm F1.2. Hopefully this lens will allow wide-field images that go even fainter.

In The Sky This Month – March 2009

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of March 2009. This month sees the end to Venus’ reign over the evening sky. Also Comet Lulin should continue to be bright enough for easy evening observation.

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

Venus has been putting on quite a display for the past few months in the evening sky. Unfortunately, the show comes to an end this month. At the beginning of the month, Venus is still riding high in the western sky after sunset. As the month progresses, it will appear lower and lower in the sky. Most people will have a hard time seeing it by mid-month. On March 27, Venus will pass between closest to the Sun. After that date, it will become a morning object. Early hour risers will witness Venus in all of its glory for most of the rest of the year.

This month Saturn will at opposition. The exact date being March 8. Opposition is when a planet (or comet or asteroid) is located opposite the direction of the Sun. On this date, Saturn will be closest to Earth and at its brightest. It rises at sunset and by 9pm is high enough to be easily seen. Even at its brightest, Saturn is not as brilliant as Venus or Jupiter. Still at magnitude +0.5, it is brighter than all but the 9 or 10 brightest stars.

The evening sky for March 15 at 9:45 pm. Chart produced with the Stellarium planetarium program.

This opposition is actually one of Saturn’s dimmest. 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.

Jupiter and Mars are located near each other low in the early morning sky. As the month progresses Jupiter will become easier and easier to see. At magnitude -2.1, Jupiter is brighter than any star in the sky.  Mars on the other hand will only be visible to those with a clear view of the southeastern horizon. At magnitude 1.2, Mars would just crack the Top 20 in brightest stars in the sky.

Early morning sky right before dawn on March 15. (produced with Stellarium)

Mercury is still visible low in the east just before dawn. Due to the angle of the ecliptic with the morning eastern horizon this month, Mercury is a very difficult object to observe from the Northern Hemisphere but an easy object from the Southern Hemisphere. It will be lost to Northern observers a few days into the month. Southern observers will be able to follow it till a bit past mid-month.

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 November, six (6) 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.

Delta Leonids (DLE)

The Delta Leonids are another minor shower with a period of activity from February 15 to March 10. Near its February 25 peak, rates may reach a paltry 2 per hour.

Gamma Normids (GNO)

This shower is best from the Southern Hemisphere since it radiates from the southern constellation of Norma. Observers north of +40 deg North will not be able to see any GNOs. Then again it is such a minor shower that there is doubt whether it even exists!

The shower spans from Feb 25 to March 22 with a peak around March 13 with a maximum ZHR of 4.

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)

Comet Lulin starts the month as a barely naked eye comet at magnitude 5. More on this comet can be found in the next section.

Binocular Comets (V < 8.0)

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 currently around magnitude 5.2 which makes it an easy object for binoculars and small telescopes from a dark sky. From a dark rural moon-less sky, it can even be seen with the naked eye. Over the course of the month, the comet will fade from naked eye view but still be bright enough for binocs/small telescopes. By the end of the month, Lulin will be close to 7th magnitude.

After a few months as a morning object, Lulin spends all of March visible in the evening. Due to its retrograde orbit, the comet is moving in almost the exact opposite direction as the Earth. As a result, it is rapidly moving to the west every night. Over the course of the month, Lulin will start the month in western Leo, cross Cancer and end in the middle of Gemini.

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.

Small Telescope Comets (V < 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 9.7 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 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.

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.

Comet 144P/Kushida

Comet Kushida was discovered by Japanese amateur astronomer Yoshio Kushida back on 1994 January 8. With an orbital period of 7.6 years, this year marks its 3rd appearance since discovery.

The comet was not expected to get brighter than magnitude 10 or 11 but recently observers have estimated it is as bright as magnitude 9.1. With perihelion this January 26 at 1.44 AU from the Sun, the comet should start to rapidly fade. The comet starts the month near the border of Taurus and Orion before moving across the “club” of Orion and into Gemini.

A finder chart for Comet Kushida 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 6.9 to 7.4 as it moves into Leo Minor, 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 Lepus and entering southern Orion. It fades from  magnitude 8.4 to 8.7 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.

(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. On October 30, Vesta was at opposition (directly opposite from the Sun in the sky) and at its brightest. This month Vesta is an evening object moving through Aries before entering Taurus near the end of the month. It will fade from magnitude 8.3 to 8.5.

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.

(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 9.9 to 9.2 as it travels through Virgo. Next month it will reach its brightest on April 21 at magnitude 8.9.

(27) Euterpe

Euterpe was the 27th asteroid discovered when it was first seen in 1853. It is an S-type asteroid with a stoney or silicate composition. With a diameter of 58 miles (96 km) it is much smaller than Ceres, Pallas or Vesta. The reason it can get as bright as them is due to its orbit which brings it closer to the Sun and Earth. This month Euterpe will be roughly 1 AU from Earth and 2 AU from the Sun.

This month Euterpe is located in Cancer not far to the east of the Beehive Star Cluster. It starts the month at magnitude 9.7 and fades to 10.5 making this an object for advanced observers.

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 Euterpe from Heavens Above.

(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.

Ampitrite reaches it brightest for the year on March 22 at magnitude 9.1. It starts the month at mag 9.7, brightens to 9.1 at opposition and fades back to 9.4 at month’s end. It spends the entire month in Virgo.

Comet Lulin Flys By Saturn

A quick reminder that bright Comet Lulin will be easy to locate tonight as it passes within a few degrees of Saturn. The comet is currently around 5th magnitude. This means observers at dark rural sites will be able to see the comet with their naked eyes as a faint glow. Observers in suburban and urban settings will be able to see the comet with small binoculars. Of course, if you have a telescope the view will be even better.

The comet will still be close (though moving away from) Saturn over the next few days.

If anyone gets a nice picture of the Comet and/or Saturn and wishes to share them, post a link to the image in the comments section and I’ll include them in a future posting.

Sky chart showing the position of Comet Lulin and Saturn for 10 pm on the night of Feb 23. Chart produced with the Stellarium software (www.stellarium.org).

More on Comet Lulin can be found here at the “In The Sky This Month – February 2009” post.

A higher resolution finder chart for observers with binoculars or telescopes can be found at Heavens Above.

A great series of images can be found at Spaceweather.com.

In The Sky This Month – December 2008

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of December 2008. The biggest event of the month will be the Venus-Jupiter-Moon conjunction on the 1st. On the 13th, the Geminid meteor shower will peak. Though usually one of the best showers of the year, the Full Moon will ruin the show.

Planets

Venus and Jupiter start off the month in grand fashion. On the 1st, the two are located in the south-southwest just after sunset within 2 degrees of each other. Venus is by far the brighter of the pair. Not that Jupiter is a slouch only being the brightest “star” in the sky after Venus. To add to the sight, a thin crescent Moon will be located just to the upper left of the pair.

As the month progresses, Venus will rapidly move away from Jupiter. Venus will appear to start each evening higher and higher in the sky. Jupiter, on the other hand, will quickly drop towards the horizon and by the end of the month, will be located close to the southwest horizon. But Jupiter will not be alone and ends the month within 1.3 degrees of the innermost planet Mercury. The Moon can also be used at the end of the month to find the evening planets as it passes close to Jupiter and Mercury on the 29th and Venus on the 31st.

This month, Saturn starts to rise before midnight. The best time to observe it, though, is just before the start of dawn when it will be located high in the sky in the constellation of Leo. The Moon will pass close to Saturn on the nights of the 18th and 19th.

Mars is too close to the Sun to be seen.

Meteors

The month of December experiences 2 major showers, the Geminids and the Ursids, and a slew of minor ones.

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, twelve (12) or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Geminids (GEM)

Along with the Perseids of August, the Geminids are one of the best meteor showers delivering great displays year after year. Unfortunately, this year sees the worst circumstances possible for Geminid watching as the nearly Full Moon is located right next to the radiant. Similar circumstances occurred in October for the Orionids but observers were still able to see quite a few meteors.

According to Sirko Molau’s analysis of video data, the Geminids are already observable at the beginning of the month though their rates are very low. The peak is predicted for the nights of December 13-16. With a radiant near the star Castor in the constellation of Gemini, the Geminids are one of the rare major showers that are observable before midnight and can be observed as early as 8:00 pm though rates are usually best after 10:00 pm. Under a dark rural moon-less sky, the Geminids can produce as many as 100+ meteors per hour. With the bright Moon, rates of a few tens of meteors per hour may still be observed.

The Geminids are the result of the break-up and subsequent activity of the “asteroid” Phaethon. Why asteroid in quotes? Most meteor showers come from comets yet Phaethon is on a very non-cometary orbit and has never shown any cometary activity. There is still much scientific discussion about what exactly Phaethon is.

More details on the Geminids and their parent “asteroid” Phaethon will be posted as we get closer to its peak.

Ursids (URS)

The Ursids will produce up to 10 meteors per hour at their peak on December 22-23. That rate makes it a borderline major/minor shower though the Ursids have experienced a number of outbursts in the past. With a radiant near the “bowl” of Ursa Minor (the “Little Dipper”), this shower is also observable all night long though the best time to observe it is during the last hours of the night. More details on the Ursids and their parent comet, Comet Tuttle, will be posted later.

Minor Meteor Showers

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

December Phoenicids (PHO)

The December Phoenicids (also just called the Phoenicids) radiate from the far southern constellation of Phoenix. Due to its southern radiant, this shower is very difficult to observe from the Northern Hemisphere. The shower results from the break-up or splitting of Comet P/1819 W1 (Blanpain) in 1819. Most years the shower only produces a few meteors per hour but on occasion up to 100 meteors per hour have been seen (1887, 1938 and 1956). No further outbursts are predicted until 2050 though that doesn’t mean we can’t be surprised. The shower is predicted to peak on December 6. In 2003, the barely active nucleus of Comet Blanpain was re-discovered by the Catalina Sky Survey.

Puppid/Velids (PUP)

These showers are another two for the southern hemisphere. There is evidence that the Puppids and the Velids are part of a much larger complex of showers that span from November through February. Their orbits suggest they are the result of the break-up of a yet-to-be-discovered comet or asteroid on a high inclination orbit (50-70 degrees). At their best, Puppid/Velids produce 5-10 meteors per hour for those south of the equator. Not too many are visible for northern hemisphere observers.

Monocerotids (MON)

The December Monocerotids (sometimes just called the Monocerotids) are produced by Comet C/1917 F1 (Mellish). Discovered in 1917 this bright comet is on a ~145 year orbit and isn’t due back till around 2062. There is evidence that this shower may have produced a number of bright fireballs during the 11th through 16th century. The shower is predicted to peak on December 7th-9th with a paltry 2 meteors per hour radiating from the faint constellation of Monoceros (located just east of Orion).

σ-Hydrids (HYD)

With a peak on December 9th of only 3 meteors per hour, these meteor from the “head” of the constellation of Hydra will be difficult to observe by all but the most advanced observers. Not much is known about this shower other than it was created by an unknown long-period or Halley-type comet with a perihelion of ~0.25 AU and an inclination of ~125 to 130 degrees.

Coma Berenicids (COM)

The Coma Berenicids are another minor shower with rates of ~5 meteors per hour at their peak. The shower is active from mid-December to late January as its radiant moves from southern Ursa Major through Coma Berenices and into Virgo. The shower may have been created by Comet C/1913 I (Lowe) a retrograde Halley-type comet. That is assuming Comet Lowe ever existed. There are some doubts that the comet was real since other observers were not able to observe the comet.

According to Peter Jennisken’s book “Meteor Showers and Their Parent Comets” a number of meteor outbursts seen between the years of 609 AD and 764 AD may have caused by this shower.

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

There are no comets bright enough to be seen without binoculars or a telescope.

Binocular Comets

Comet C/2007 N3 (Lulin)

The brightest comet of the month is not visible for the 1st half of the month. Comet Lulin will be too close to the Sun until after mid-month when it will be visible low in the southeast (near the “head” of Scorpius) at the start of dawn. 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. At that time the comet may be as bright as 4th magnitude making it an easy object for binoculars and small telescopes. In fact, the comet will be visible to the naked eye as a small faint fuzzball from dark sites.

In December the comet should brighten from 7th magnitude to 6th. I say “should” because the comet has not been seen since late October because it has been too close to the Sun. As a result, we don’t know how bright Lulin is right now. Baring a new discovery or unforeseen outburst, Comet Lulin may be the best comet of 2009.

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.

Small Telescope Comets

Comet C/2008 A1 (McNaught)

Comet McNaught is a long-period comet that passed closest to the Sun on Sept 29 at a distance of 1.07 AU (100 million miles or 160 million km). It was the first comet discovered in 2008 having been found by  Robert McNaught of the Siding Spring Survey back on January 10. It was McNaught’s 43rd comet discovery.

The comet is only visible from the Northern Hemisphere and during December it travels through northern Ophiuchus into southern Hercules. After getting as bright as 6th magnitude at perihelion, the comet will slowly fade from magnitude 8.8 to 10.0 during the month. This will probably be the last month to see this comet in regular sized backyard telescopes.

A finder chart for Comet McNaught 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 10.2 and will slowly brighten during the month.  It will be traveling south through the constellations of Cepheus and Lacerta and is nicely positioned for evening observing. I was able to observe the comet visually with my backyard 12″ reflecting telescope a few weeks ago. 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 the 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.

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.

Comet P/2003 K2 (Christensen)

Yet another comet discovered by Eric Christensen may be visible in backyard scopes in December. This comet is a short-period comet with a period of 5.7 years. It is very faint except when close to the Sun. With perihelion predicted for 2009 January 8 at a distance of 0.53 AU from the Sun, the comet may be bright enough for backyard observers by the end of the month.

There are a lot of question marks about this comet. It was only observed for 1 month in 2003 and those observations were made after perihelion. The comet has yet to be observed during this return and its exact location is unknown. Plus since the comet has never been observed before perihelion we don’t know how bright it should be. Hopefully the comet will be picked up in the next few weeks. When/if that happens, we’ll have a better idea of how observable it will be.

Asteroids

Binocular and Small Telescope Asteroids

(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 the surface. Ceres is one of two targets for NASA’s Dawn spacecraft which is scheduled to visit it in 2015. This month Ceres is located high in the sky right before sunrise in Leo brightening from magnitude 8.3 to 7.9.

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

(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 moves through the far southern constellations of Columba and Caelum. It peaks at magnitude 8.0 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.

(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. On October 30, Vesta was at opposition (directly opposite from the Sun in the sky) and at its brightest. This month Vesta will fade from magnitude 7.0 to 7.6 as it moves through Pisces.

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

(9) Metis

Metis was discovered in 1848 by Andrew Graham of Ireland. It is a S-type asteroid with a composition similar to stony meteorites (ordinary chondrites). With a diameter of 140×120x85 miles or 235×195×140 km, it is much smaller than Ceres, Pallas or Vesta. During the month, it will quickly fade from magnitude 9.1 to 9.8 as it travels through Aries just a few degrees northeast of Vesta.

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