In The Sky This Month – June 2009

June 2, 2009 Carl Hergenrother 11 comments

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.

Categories: Asteroids, Comets, Meteors, planets Tags: astronomy, ceres, comet cardinal, comet christensen, comet garradd, comet kopff, Comets, iris, june bootids, jupiter, mars, mercury, neptune, saturn, uranus, venus

In The Sky This Month – 2009 April

April 5, 2009 Carl Hergenrother 18 comments

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.

0422venus1

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)

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.

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.

flora_irene_april

(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.

eunomia_april

(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.

amphitrite_april

Categories: Asteroids, Comets, Meteors, planets Tags: amphitrite, astronomy, ceres, comet christensen, comet itagaki, comet lulin, comet yi-swan, Comets, eunomia, flora, irene, jupiter, lyrids, mars, mercury, Meteors, moon, occultation, pallas, pi puppids, planets, venus, vesta

In The Sky This Month – March 2009

March 1, 2009 Carl Hergenrother 5 comments

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.

venussaturn_200902261

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.

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)

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)

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.

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

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

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.

Categories: Asteroids, Comets, Meteors, planets Tags: amphirite, astronomy, ceres, comet christensen, comet kushida, comet lulin, Comets, euterpe, irene, Meteors, pallas, planets, saturn, venus, vesta

The Sky Tonight – Feb 28

March 1, 2009 Carl Hergenrother 3 comments

I hope everyone was able to see the spectacular conjunction between Venus and the Moon. Even to this sometimes jaded astronomer, it was quite a sight to see. Right now it is the highlight of the year so far. But as nice as it looked, there will be an even better Venus-Moon pair-up in 2 months. You’ll need to get up in the early hours of the morning, but mark April 22 on your calendars. On that date, all of North America will see the Moon and Venus even closer to each other. And for central and western North America, the Moon will pass in front of (or occult) Venus. As a teaser, here what the view will be from Tucson at 5:00 am on April 22. Note, Mars will also be nearby with Jupiter visible many degrees away.

The Venus-Moon (and Mars) conjunction that will take place on 2009 April 22. Image shows the scene over Tucson at 5:00 am that morning. Image from the Stellarium program (www.stellarium.org).

Tonight, the Moon has moved quite a bit away from Venus. It will not be quite the striking site it was last night but should still be impressive. A chart showing the relative position of Venus, the Moon, Comet Lulin, Saturn and the brighter stars can be seen below.

Night sky on the evening of Feb 28 at 8:15 pm. Image made with the Stellarium software program (www.stellarium.org).

Comet Lulin continues to move rapidly to the west. Remember it was only a few days ago when the comet was right next to Saturn. Last night it was practically on top of Regulus, the brightest star in Leo. If you haven’t seen the comet, don’t wait. The comet is still at its brightest but will start to fade rapidly. That and the bright Moon for the next 2 weeks will make Lulin a tough site to see without a good sized pair of binoculars or telescope. Right now Lulin is a difficult naked eye object from a very dark site and an easy binocular object from just about anywhere.

Categories: Asteroids, Comets, planets Tags: astronomy, ceres, comet lulin, venus

In the Sky This Month – January 2009

January 1, 2009 Carl Hergenrother 90 comments

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of January 2009. The month starts off with Mercury and Jupiter close together in the evening sky. January also has one major meteor shower, the Quadrantids on Jan 3/4.

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 rules the month of January. Located about 30-40 degrees above the southwest horizon, Venus is the brightest “star” in the sky for the first few hours of the night. Through a telescope, Venus appears like a brilliant half moon. The Moon will pass within 2.5 degrees of Venus on the night of the 30th.

Jupiter is located well below Venus in the west-southwest during the first week of January. After that Jupiter will be too close to the Sun to be seen.

Mercury is also visible a few degrees above Jupiter during the 1st week or so of January. It will be furthest from the Sun on the 4th and highest above the horizon on the 6th. By mid-month, Mercury will be too close to the Sun to be seen.

This month Saturn rises in the east around 11pm on the 1st and 9pm on the 31st. The best time to observe it, though, is when it is located directly overhead (5am on the 1st and 3am on the 31st). The Moon will pass close to Saturn on the night of the 15th.

Mars is still too close to the Sun to be seen.

Meteors

The month of January experiences 1 major shower, the Quadrantids, and only a few 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, six (6) or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Quadrantids (QUA)

The Quadrantids are the best shower that you’ve probably never heard of. It’s bad enough that this shower peaks in the middle of winter in the northern hemisphere, but it is also named after a long defunct constellation. When first identified in the early 1800s, the meteors were observed to radiate from the small faint constellation of Quadrans Muralis (the Mural Quadrant). Unfortunately, the constellation didn’t make the cut when the official list of 80 constellations was set in 1930. Today, Quadrans Muralis and the radiant of the Quadrantids can be found north of the constellation of Bootes.

Another strike against observing the Quadrantids is their short duration. Showers, like the Perseids and Orionids, produce high rates of meteors for a few days near their maximum. The Quadrantids are only highly active for 12-24 hours. As a result, the shower can be missed if the peak does not coincide with your early morning observing.

This year there are 2 predictions for the peak. Based on past Quadrantid peaks, the International Meteor Organization predicts a peak on January 3 at 12h 50m UT. That’s 5:50 am MST or 4:50 am PST. If this prediction is correct, the Quadrantids will be best over western North America and probably pretty good for all of North America.

A second prediction is based on work by Jeremie Veubaillon and published in a chart in Peter Jenniskens’s book “Meteor Showers and Their Parent Comets”.It predicts an earlier peak on January 3 at ~1:00 UT. That’s in the early evening for North America at a time when the shower will not be easily visible. The Veubaillon prediction is based on all of the Quadrantids having been released during the break-up of a comet in 1490.

Last year rates reached as high as ~80 meteors per hour under a dark sky. Like most meteor showers, the Quadrantids are only observable early in the morning a few hours before dawn. The International Meteor Organization will post up-to-date observations of the activity level at their ZHR Live site.

Where do the Quadrantids come from? According to Peter Jenniskens, the Quadrantids are the result of an outburst of material or even the break-up of a comet in 1490. This comet was observed by Chinese, Korean and Japanese astronomers. In 2003, a new asteroid was discovered named 2003 EH1. It now appears that 2003 EH1 is either the same as the comet seen in 1490 or the largest surviving piece of that comet.

Minor Meteor Showers

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

Coma Berenicids (COM)

The Coma Berenicids are a 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.

Comets

Naked Eye Comets (V < 6.0)

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

Binocular Comets (V < 8.0)

Comet C/2007 N3 (Lulin)

The brightest comet of the month can be seen low in the southeast right before dawn. Starting the month near the “head” of Scorpius, the comet will move into and cross the constellation of Libra during the month. 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.

The comet is currently around magnitude 7.5 which makes it an easy object for binoculars and small telescopes from a dark sky. By the end of the month, it should be around magnitude 6 and perhaps visible to naked eye observers in very dark skies.

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)

The comet is currently around magnitude 10.2 and will slowly brighten during the month. It will be traveling south through the constellation of Lacerta and is nicely positioned for evening observing. 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 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 C/2006 OF2 (Broughton)

Similar to Comet C/2006 W3 (Christensen), C/2006 OF2 (Broughton) is another intrinsically bright comet with a large perihelion distance. It was the 2nd comet discovered by amateur astronomer John Broughton of Queensland, Australia. He first saw it on 2006 July 17 with a CCD-equipped 0.25-m telescope. At first, no cometary activity was detected and the object was classified as an asteroid. In late September of 2006, I was able to find evidence of cometary activity on images taken with the University of Arizona 1.54-m and the object was reclassified as a comet.

Comet Broughton passed perihelion on 2008 September 15 at a distance of 2.43 AU from the Sun. Based on its prior brightness behavior, it was not expected to be brighter than 10th magnitude. In the past few weeks, the comet has experienced a minor outburst in brightness. At its current magnitude of 9.8, the comet can be seen in large backyard telescopes. Moving south through the constellation of Auriga, the comet should fade as it moves away from both the Sun and Earth.

A finder chart for Comet Broughten 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 8.8. With perihelion this January 26 at 1.44 AU from the Sun, the comet may brighten a little more over the next few weeks. It is currently retrograding through western Taurus.

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.

Comet 210P/Christensen

Yet another comet discovered by Eric Christensen may be visible in backyard scopes in January. This comet is a short-period comet with a period of 5.7 years. It is very faint except when close to the Sun. Perihelion occurred on December 19 at a distance of 0.53 AU from the Sun.

Alan Watson found Comet 210P/Christensen on images taken by the STEREO-B spacecraft on 2008 December 8 and 9. At the time, he thought the comet might be new until Maik Meyer suggested the STEREO comet was actually Comet 210P/Christensen. STEREO (which stands for Solar TErrestrial RElations Observatory) is a NASA mission to study the Sun and its immediate environment. Though not designed specifically to observe comets, its cameras have the ability to pick up bright comets close to the Sun. Quite often, these comets are too close to the Sun to be seen from Earth due to the scattering of sunlight by Earth’s atmosphere.

Though too close to the Sun to be seen from Earth, another spacecraft was able to see the comet as it sped past the Sun. Observations by the SOHO spacecraft estimated that the comet reached a brightness of 6th magnitude. The comet may still be bright enough for large backyard telescopes during the 1st half of January. The comet should be 9th-10th magnitude as it speeds through the constellation of Ophiuchus in the pre-dawn sky.

Asteroids

Binocular and Small Telescope Asteroids (V < 10.0)

(1) Ceres

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 moves through the far southern constellations of Caelum and Eridanus. It fades from magnitude 8.0 to 8.2 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 will fade from magnitude 7.6 to 8.1 as it moves from Pisces into Cetus.

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.

(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 75 miles (125 km) it 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 will brighten from magnitude 9.7 to 8.9 as it moves from Leo into Cancer. The asteroid will be at its brightest in early February at magnitude 8.8.

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.

(40) Harmonia

[Thanks to Sam Millar for calling attention to this asteroid.]

Harmonia just barely makes the cut this month. Starting the month at magnitude 9.9, it peaks in brightness on January 12 at 9.5. By the end of the month, Harmonia is back below 10th magnitude.

Similar to Euterpe, Harmonia is a stoney silicate-rich S-type in the inner Main Belt. At opposition on the 12th, it will be 2.30 AU from the Sun and 1.31 AU from Earth.

Finder chart for Harmonia from Heavens Above.

Categories: Asteroids, Comets, Meteors, planets Tags: Asteroids, astronomy, broughton, ceres, christensen, Comets, euterpe, harmonia, kushida, lulin, Meteors, pallas, planets, quadrantids, vesta

In The Sky This Month – December 2008

December 1, 2008 Carl Hergenrother 3 comments

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.

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.

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)

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.

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

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

Categories: Asteroids, Comets, Meteors, planets Tags: Asteroids, astronomy, ceres, christensen, Comets, geminids, jupiter, lulin, mcnaught, mercury, Meteors, metis, planets, saturn, ursids, venus, vesta

In The Sky This Month – November 2008

November 1, 2008 Carl Hergenrother 4 comments

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of November 2008.

Planets

Venus is the very bright “star” close to the southwestern horizon for an hour or so after sunset. When it is above the horizon, it is the brightest “star” in the sky. Every night Venus will appear to be a little bit higher in the sky. As the month progresses Venus will also appear a little further to the south. Venus starts the month in the constellation of Ophiuchus. It crosses into Sagittarius by the 2nd week of the month. By the end of the month, Venus will be located very close to Jupiter (within 2 degrees).

Jupiter is located in the constellation of Sagittarius. At the beginning of the month, Jupiter starts the night low in the southwestern sky and sets around 9 pm. As the month progresses, it will appear lower in the sky and further to the west. Jupiter is fainter than Venus but brighter than any star. As mentioned in the Venus section above, Jupiter will close in on Venus all month. By the end of the month, Jupiter and Venus will be located within 2 degrees of each other.

Saturn is located high in the east just before sunrise in the constellation Leo. It is as bright as many of the brightest stars.

Mercury is located low in the east-south-east right before sunrise. By the 2nd week of the month it is too close to the Sun to be seen. Mercury won’t be observable again until mid-December.

Mars is too close to the Sun to be seen.

Meteors

November sees a number of meteor showers including the Leonids which have produced spectacular storms in the past.

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, sixteen (16) 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 2008 bring? Well first off, this is a bad year with regards to the Moon. Similar to October’s Orionids, the Moon will be bright and close to the Leonid radiant during their peak limiting the number of fainter meteors that can be seen. In a normal year, the Leonids produce maximum rates of ~10-15 meteors per hour. The Moon will cut those rates in half or more.

There are 2 predictions for enhanced activity this year. The International Meteor Organization summarizes this year’s prediction with the following taken from their 2008 Meteor Calendar:

The Leonids may produce just a normal maximum close to their ‘traditional’ nodal time in 2008, on November 17, around 09h UT, though the bright waning Moon will be a severe problem if so. However, Mikhail Maslov proposed that the shower may show a peak with ZHRs ~ 130 at 00h22m UT on November 17 in WGN 35:1 (2006, p. 7), with meteors brighter than average. Many of his other model calculations for the Leonids in the period 2001 — 2006 showed some differences to what was actually observed, so while this this is an interesting possibility for 2008, its accuracy is unknown and unproven. Jérémie Vaubaillon finds instead two potential stream encounters, centred on November 17 at 01h32m UT (1466 trail; ZHR most uncertain — perhaps ~ 50, but maybe ~ 25 — 100) and November 18 at 21h38m UT (1932 trail; ZHR possibly ~ 20 at best?). Checking on all these times (or any others that may be suggested subsequently) will be difficult due to the Moon, but valuable.

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 low rates due to the bright Moon. For those located throughout Eurasia, one, two or three of the possible outbursts may be observable. 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.

Orionids (ORI)

When you see an Orionid meteor, you are seeing small pieces of Halley’s Comet which were released thousands of years ago. The Orionids were the best shower during the month of October. At their peak, Orionids appear to radiate from a point in the constellation of Orion, hence the name Orionids. Meteor shower radiants are not stationary and on average move about a degree per day towards the east. As a result, in November the Orionids actually appear to radiate from the southwestern Gemini. Though they peaked around Oct 21, a few Orionids will be observable after midnight till the middle of November.

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.

Comets

Naked Eye Comets

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

Binocular Comets

Comet C/2008 A1 (McNaught)

Comet McNaught is a long-period comet that will 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 Jan 10. It was McNaught’s 43rd comet discovery.

The comet is only visible from the Northern Hmisphere and during November it crosses the constellation of Ophiuchus. The comet will slowly fade from magnitude 7.5 to 8.5 during the month. I was able to observe this comet with my 12″ Dobsonian from my backyard in Tucson. The comet was not an easy object to see even in a large telescope from a site with moderate light pollution. Dark skies will definitely help with this one. From dark skies, it can be seen in binoculars or a small telescope. From brighter skies, a telescope is required.

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

Small Telescope Comets

Comet 6P/d’Arrest

Comet 6P/d’Arrest was one of the first short-period comets to be observed. First seen by the Frenchman Philippe de la Hire in 1678, the comet was definitively discovered by Heinrich Louis d’Arrest of Germany on 1851 June 28.

Comet d’Arrest is in a short-period orbit with a period of 6.5 years. It passed closest to the Sun back on Aug 14 at a distance of 1.35 AU (125 million miles or 200 million km). The comet is a very difficult object for observers in the Northern Hemisphere because it is located in the southern constellation of Sculptor. Even though it will slowly move north this month, observing conditions will not improve because the comet will also fade from magnitude ~9.5 to ~11.0 by month’s end. This comet will definitely require a telescope and dark skies to be seen.

A finder chart for Comet d’Arrest 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

(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 low in the eastern sky right before sunrise in Leo brightening from magnitude 8.6 to 8.4.

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 from the southern constellation of Lepus into the even further southern constellation of Columba. It brightens from magnitude 8.2 to 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 6.5 to 7.0 as it moves through Cetus.

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. Metis will be at opposition and also at its brightest (magnitude 8.5) on November 4. Opposition is also the moment when Metis will be closest to Earth this year at a distance of 1.14 AU. During the rest of the month, it will slowly fade to magnitude 9.1 as it travels through Aries just a few degrees south 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.

Categories: Asteroids, Comets, Meteors Tags: Asteroids, astronomy, ceres, Comets, d'arrest, leonids, mcnaught, Meteors, metis, pallas, sporadics, taurids, vesta

In The Sky This Month – October 2008

October 1, 2008 Carl Hergenrother 11 comments

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of October 2008.

Planets

Venus is the very bright “star” close to the southwestern horizon for an hour or so after sunset. When it is above the horizon, it is the brightest “star” in the sky.

Jupiter is located in the constellation of Sagittarius. At the beginning of the month, Jupiter starts the night almost due south in the southern part of the sky. As the night progresses, it slowly moves to the west and sets around 11 pm local time. By Halloween, Jupiter starts the night low in the southwestern sky and sets around 9 pm. Jupiter is fainter than Venus but brighter than any star.

Saturn is located low in the east just before sunrise. It is as bright as many of the brightest stars.

Mercury is too close to the Sun at the beginning of the month. By the mid-month, it will become observable as a bright “star” low in the ESE sky just before sunrise. It reaches the best time for observation on Oct 22 when it is furthest from the Sun. It will continue to be observable for the rest of the month as it slowly drops towards the horizon.

Mars is too close to the Sun to be seen.

Meteors

October sees a number of meteor showers including one of the year’s best, the Orionids.

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 October, ten (10) or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Orionids (ORI)

The Orionids are the best shower during the month of October. When you see an Orionid meteor, you are seeing small pieces of Halley’s Comet which were released thousands of years ago. The Eta Aquarids of May are also from Comet 1P/Halley.

This shower is active from Oct 3 to Nov 11 with a broad peak between Oct 18 and 24. They radiate from northern Orion. During their peak, rates can be as high as 30-100 meteors per hour. Last year rates reached 70 meteors per hour and similar circumstances are predicted for this year with the best time being the morning of Oct 19 (for the US). However, a bright quarter Moon will wash out many of the fainter meteors resulting in smaller rates. Much of this year’s ORI meteors were released by Comet 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).

Minor Meteor Showers

Minor showers produce so few meteors that they are barely noticeable above the background of regular meteors.

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. They are active for the entire month of October with activity slowly building as the month progresses. Though named after the constellation of Taurus, the Taurids radiate from the constellation of Aries for most of October.

Delta Aurigids (DAU)

Until a few years ago, the September Perseids and the Delta Aurigids were considered part of the same shower. Analysis of the orbits of their meteors suggested that there are in fact two overlapping showers each originating from a different unknown long-period comet. Like the SPEs, this minor shower usually produces no more than ~3 meteors per hour at its maximum. There is some disagreement as to when this shower is active. Naked eye observations over the past few decades suggest a period of activity from Sept 18 through Oct 10 with a broad peak between Sept 23 and Oct 3. Recent video data finds a later period of activity between Oct 6 and 12 with no obvious peak. The DAUs radiate from the northern part of the constellation of Auriga just to the north of the bright star Capella.

October Camelopardalids (OCT)

This is a new shower first recognized in 2005, though sightings as early as 1902 have been recorded. A few OCAs are observable between Oct 1 and 10. The vast majority of meteors occur during a short ~2 hour span at the time of peak activity. This year’s peak is predicted to occur within a few hours of ~14:00 UT (7:00 am PDT) on October 5. Unless the peak comes early it will occur after sunrise for observers in the western US. The peak time suggests a nice, but short, shower may be visible across the northern Pacific basin and in northeastern Asia. Since Camelopardalis is a far northern constellation, this shower is not visible from the Southern Hemisphere.

Draconids (Giacobinids) (GIA)

The Draconids have produced some of the highest rates of meteor activity in history. In both 1933 and 1946 rates were greater than 10,000 meteors per hour. Impressive rates of greater than 500 meteors per hour were also observed in 1952, 1985 and 1998. Unfortunately, this shower barely produces any meteors in non-storm years. What will this year hold in store? There are no predictions for any enhanced activity this year but we won’t know for sure unless we watch. This is another shower only observable from the Northern Hemisphere. It radiates from the constellation of Draco.

The Draconids are also known as the Giacobinids because they are produced by Comet 21P/Giacobini-Zinner. This comet was discovered by the same late 19th/early 20th century astronomer who found the recently re-discovered Comet 205P/Giacobini.

Epsilon Geminids (EGE)

This is an early morning shower which radiates from the constellation Gemini. It is visible between Oct 5 and 22 with a peak on Oct 14. At its best, only about 2 meteors per hour are visible.

Leo Minorids(LEO)

Yet another early morning shower, this time radiating from Leo Minor, a faint constellation just north of Leo. It is visible between Oct 17 and 27 with a maximum rate of only ~2 meteors per hour occurring on Oct 24.

Comets

Naked Eye Comets

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

Binocular Comets

Comet C/2008 A1 (McNaught)

Comet McNaught is a long-period comet that will pass 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 Jan 10. It was McNaught’s 43rd comet discovery.

Since discovery this comet could only be seen from the Southern Hemisphere. This month it moves rapidly to the north and is easily visible from the Northern Hemisphere by mid-month. During October, the comet travels through the constellations of Libra and Ophiuchus. The comet is as bright as it is going to get at magnitude 6.5. A comet of this brightness can be seen in binoculars or a small telescope.

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

Small Telescope Comets

Comet 6P/d’Arrest

Comet d’Arrest is in a short-period orbit with a period of 6.5 years. It passed closest to the Sun back on Aug 14 at a distance of 1.35 AU (125 million miles or 200 million km). Comet d’Arrest starts the month in the southern constellation of Grus before entering Sculptor near months end. The comet is a very difficult object for observers in the Northern Hemisphere. With a brightness of magnitude 8.5 it will require a telescope to be seen though observers at very dark sites may be able to see it in binoculars.

A finder chart for Comet d’Arrest 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

(1) Ceres

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 is located in the southern constellation of Lepus and brightens from magnitude 8.7 to 8.2 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. This month it is located in Cetus and brightens from magnitude 6.9 to 6.4 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.

(9) Metis

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

Categories: Asteroids, Comets, Meteors Tags: Asteroids, astronomy, ceres, Comets, d'arrest, delta aurigids, draconids, encke, epsilon geminids, halley, leo minorids, mcnaught, Meteors, metis, october camelopardalids, orionids, pallas, planets, taurids, vesta

In The Sky This Month – Rest of September 2008

September 16, 2008 Carl Hergenrother Leave a comment

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

Meteors

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, ten (10) or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

There are no major meteor showers visible during the month of September.

Minor Meteor Showers

Minor showers produce so few meteors that they are barely noticable above the background of regular meteors.

September Perseids (SPE)

The September Perseids which experienced a surprise outburst of activity on Sept 9 are winding down. By Sept 17 they should no longer be active.

Delta Aurigids (DAU)

Comets

Naked Eye Comets

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

Binocular Comets

Comet C/2008 A1 (McNaught)

Comet McNaught is a long-period comet that will pass 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 Jan 10. It was McNaught’s 43rd comet discovery.

Currently the comet can only be seen from the Southern Hemisphere. Next month the comet will be visible for observers in the Northern Hemisphere as an early evening object. As of Sept 16, the comet is located in the constellation of Centaurus. By months end it will clip the southeast corner of Hydra and enter Libra. The comet is as bright as it is going to get at magnitude 6.5. A comet of this brightness can be seen in binoculars or a small telescope.

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

Small Telescope Comets

Comet 6P/d’Arrest

Comet d’Arrest was one of the first short-period comets to be observed. First seen by the Frenchman Philippe de la Hire in 1678, the comet was definitively discovered by Heinrich Louis d’Arrest of Germany on 1851 June 28.

Comet d’Arrest is in a short-period orbit with a period of 6.5 years. It passed closest to the Sun back on Aug 14 at a distance of 1.35 AU (125 million miles or 200 million km). Currently located in the southern constellation of Grus, the comet is a very difficult object for observers in the Northern Hemisphere. With a brightness of magnitude 8.5 it will require a telescope to be seen though observers at very dark sites may be able to see it in binoculars.

A finder chart for Comet d’Arrest 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

(1) Ceres

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 is located in the southern constellation of Lepus at magnitude 8.7-8.8.

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. This month it is located in Cetus at magnitude 7.0.

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

Categories: Asteroids, Comets, Meteors Tags: Asteroids, astronomy, ceres, Comets, d'arrest, delta aurigids, mcnaught, Meteors, pallas, september perseids, vesta

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