In The Sky This Month – May 2010

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of May 2010. Venus continues to ascend higher in the evening sky and is the brightest star during early evening hours. The major meteor shower, Eta Aquariids, will be washed out by a bright Last Quarter moon.

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

Planets

Venus – Venus is the brilliant star low in the west during the early evening hours. It sets about 2 and half hours after the Sun. Venus will only get a little higher next month. From now till July/August it will ride as high as it’ll get for this apparition for northern observers. In fact, this is not a very good evening apparition for Venus. On the other hand, it is a great apparition for observers south of the Equator. For you, Venus will continue to climb till late August.

May 16 - Moon passes within 0.6° from Venus

Mars – This month the Earth and Mars continue to move further apart. As a result, Mars will continue to fade from magnitude +0.7 to +1.1. Still it will be a bright red beacon nearly overhead right after sundown. It’s brightness is comparable to that of the other bright stars. Note that unlike the stars which twinkle, Mars shines with an unwavering red glow.

May 20 - Moon passes within 5° of Mars

Saturn – Saturn was at opposition in Virgo on March 21. This month Saturn is visible in the east-southeast during the early evening hours. It will slowly fade from magnitude +0.8 to +1.0 throughout the month. Telescope users should note that Saturn’s rings are still within a few degrees of edge-on.

May 22 - Moon passes within 8° of Saturn

JupiterJupiter once again returns to sight as a brilliant star low in the east-southeast before dawn. The magnitude -2.2 planet will get brighter and better place for observing over the next few months.

May 9 - Moon passes within 6° of Jupiter

Mercury -Mercury will rise out of the dawn sky toward the end of the month. This morning apparition will not be good for northern observers.

May 12 - Moon passes within 8° of Mercury

Meteors

May starts to see an increase in meteor activity after a few months of low activity. The year is usually split in 2 with January through June having low rates with few major showers while July through December (really through the 1st week of January) have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During May, 10-12 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Eta Aquariids (ETA)

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

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

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

Additional information on these showers and other minor showers not included here can be found at the following sites: Robert Lunsford’s Meteor Activity Outlook.

Minor Meteor Showers

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

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

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V = 6.0 – 8.0)

Comet C/2009 R1 (McNaught)

There are 2 comets bright enough to be seen in small telescopes this month. Both were discovered by Rob McNaught of Australia during the Siding Spring Survey. As a result, both comets go by the moniker of Comet McNaught though they do have different designations [Comet C/2009 K5 (McNaught) and Comet C/2009 R1 (McNaught)].

The comet that should end the month as the brightest is Comet C/2009 R1 (McNaught). This comet was found on Sept. 9, 2009 with the 0.5-m Uppsala Schmidt telescope from Australia. At the time, the comet was a faint 17th magnitude.

Perihelion will be on July 2nd of this year at a relatively small distance of 0.41 AU from the Sun. This month it will be 1.44 AU from the Sun and 1.96 AU from Earth on May 1st, 1.19 AU from the Sun and 1.61 AU from Earth on the 15th, and 0.90 AU from the Sun and 1.28 AU from Earth on the 31st. Currently the comet is around magnitude 10.0 and should brighten to ~7.0 by the end of the month. 10th magnitude requires a small telescope but under dark skies while 7th magnitude should be easy for small telescopes under most sky conditions and binoculars under a dark sky. It is a morning object as it moves from Pisces, through Pegasus and into Andromeda.

This comet may even brighten to naked eye brightness (under very dark skies) in June. Of course with relatively small comets getting this close to the Sun, there is always a chance the comet will break up and disintegrate before it gets too bright (as C/2009 O2 did last month).

Orbits and position of Comet C/2009 R1 and the planets for May 15, 2010. Image created with C2A. Credit: Carl Hergenrother.

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.

Small Telescope Comets (V = 8.0 – 10.0)

Comet C/2009 K5 (McNaught)

The 2nd ‘Comet McNaught’  is Comet C/2009 K5 (McNaught). It was discovered on May 27, 2009 deep in the southern sky. Similar to C/2009 R1, this comet was also found with the Uppsala schmidt at around magnitude 17.

With perihelion on April 30 of this year at a distance of 1.42 AU from the Sun, C/2009 K5 is bright enough to be seen in small backyard telescopes from dark sites. During the month it should be as bright as it gets at around magnitude 8.2 to 9.0. The comet will move through Cepheus and Camelopardalis. As the month progresses, the comet will have traveled far enough north to be circumpolar and visible all night long (for observers at northern mid-latitudes and further north).  At mid-month it will be located 1.44 AU from the Sun and 1.51 AU from Earth.

Orbits and position of Comet C/2009 K5 and the planets for May 15, 2010. Image created with C2A. Credit: Carl Hergenrother.

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.

Asteroids

Binocular and Small Telescope Asteroids (V < 9.0)

(4) Vesta

Vesta is the brightest asteroid in the Main Belt. This is due to its high albedo (or reflectivity) which causes it to reflect ~42% of the light that strikes it. Vesta is also 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 has dimensions of 347x336x275 miles or 578×560×458 km.

The maps below were created from images taken with the Hubble Space Telescope. The geography is dominated by a large impact crater located near the south pole (the blue ‘donut’ in the elevation map). Perhaps this crater is the result of the impact that blasted off the smaller V-type asteroids. We’ll know more next year when NASA’s Dawn spacecraft enters orbit around Vesta for a full year. Currently the encounter is scheduled for July 2011 to July 2012.

Images and models of the shape of asteroid (4) Vesta. In the upper left is a real HST image, to the upper right is a model of Vesta’s shape, and on the bottom is an elevation map . Credit: NASA/STScI.

Vesta starts the month at magnitude 7.3 and steadily fades to mag 7.7. A small pair of binoculars will allow you to see Vesta among the stars of Leo.

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

(2) Pallas

Pallas is a dark 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 similar in size to Vesta with dimensions of 350x334x301 miles or 582x556x501 km. The reason it is fainter than Vesta is its darker albedo of 16%. Though no spacecraft are scheduled to visit Pallas, Hubble was able to get some good images that clearly show its nearly spherical shape.

This month it fades from magnitude 8.7 to 9.0. Over the course of the month it travels north from the constellation of Serpens Caput into Corona Borealis.

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.

In The Sky This Month – April 2010

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of April 2010. This first half of the month is a great time to see Mercury, the innermost planet. It can be easily located low in the west during evening twilight right next to Venus.

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

Planets

Mercury and Venus – Venus is the brilliant star low in the west right during evening twilight. It sets an hour and a half after the Sun at the start of the month. By the end of the month, it is up for 2 hours and 15 minutes after sunset. Venus will continue to climb higher and brighten for the next few months.

Mercury is usually difficult to observe. This month, on the other hand, is a perfect time to see this elusive planet. Not only is Mercury as high above the western horizon as it can get for observers in the Northern Hemisphere, but Venus can be used to easily find it. Mercury and Venus are located within 5° of each other until April 12. Mercury is the bright, though still much fainter than Venus, “star” to the lower right of Venus. By the 2nd half of the month, Mercury will be too faint and too close to the Sun to be seen.

Apr 3 - Mercury and Venus within 3° of each other
Apr 8 - Mercury at Greatest Elongation East
Apr 15/16 - Moon passes 4° from Venus and 1.5° from Mercury

Mars – This month the Earth and Mars continue to move further apart. As a result, Mars will continue to fade from magnitude +0.2 to +0.7. Still it will be a brilliant red beacon nearly overhead right after sundown. It’s brightness is comparable to that of the other bright stars. Note that unlike the stars which twinkle, Mars shines with an unwavering red glow.

Apr 17 - Mars within 1.1° of center of Beehive Cluster
Apr 22 - Moon passes close (4°) to Mars

Saturn – Saturn was at opposition in Virgo on March 21. This month Saturn is visible low in the east-southeast during the early evening hours. It will slowly fade from magnitude +0.6 to +0.8 throughout the month. Telescope users should note that Saturn’s rings are still within a few degrees of edge-on.

Apr 25 - Moon and Saturn within 7° of each other

JupiterJupiter once again returns to sight as a brilliant star low in the east-southeast right before dawn. The magnitude -2 planet will get brighter and better place for observing over the next few months.

Apr 11 - Moon and Jupiter within 6° of each other

Meteors

April is still a time of low meteor activity though it will experience a slight uptick in activity due to the Lyrids. The year is usually split in 2 with January through June having low rates with few major showers while July through December (really through the 1st week of January) have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During April, 9-11 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. Starting this month, info on most of the minor showers will be provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

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

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V = 6.0 – 8.0)

None

Small Telescope Comets (V = 8.0 – 10.0)

Comet 81P/Wild 2

Comet Wild 2 is a short-period Jupiter-family comet on a 6.4 year orbit. In 1974 a close approach to Jupiter placed the comet on its current orbit which allows (relatively) close approaches to the Sun and Earth. Swiss professional astronomer Paul Wild found the comet photographically on its first close perihelion in 1978. During its last perihelion passage it was the target of the NASA Stardust spacecraft which flew through its coma, collected cometary dust, and returned the dust to Earth. Though Wild 2 has become bright enough to be seen in small backyard telescopes before, this year’s apparition will be its best since discovery. Not till 2042 will it come closer, and even then only marginally so.

The nucleus of comet Wild 2 taken by the Stardust spacecraft. Credit: NASA/JPL/Stardust team.

This year Wild 2 reached perihelion on February 22 at 1.60 AU while closest approach to Earth will occur on April 5 at 0.67 AU. The comet should fade this month but still be as bright as magnitude ~9.0 to 10.0 in April, it should remain brighter than magnitude 10.0 through May. At mid-month the comet a morning object located in Virgo at a distance of 1.68 AU from the Sun and 0.68 AU from Earth.

A finder chart for Comet Wild 2 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/2009 K5 (McNaught)

Comet McNaught is the brightest comet in the sky this month. It was discovered by Rob McNaught on the night of May 27, 2009 deep in the southern sky. The discovery was made with the 0.5-m Uppsala Schmidt telescope from Australia as part of the Siding Spring Survey (one of the three Catalina Sky Survey components) for unknown asteroids and comets. At the time, the comet was a faint 17th magnitude.

With perihelion on April 30 of this year at a distance of 1.42 AU from the Sun, C/2009 K5 is now bright enough to be seen in small backyard telescopes from dark sites. During the month it should be as bright as 8.0 to 8.5 magnitude as it moves north while paralleling the Milky Way in Aquila. The comet will be a morning object all month long. At mid-month it will be located 1.44 AU from the Sun and 1.27 AU from Earth.

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/2009 O2 (Catalina)

This long-period comet was supposed to be as bright as magnitude 8 this month but fell short. In fact, images taken since the middle of March suggest the comet may be slowly “fizzling out”. I plan to write a liitle more on this comet and other “disintegrating” comets in a future post.

Asteroids

Binocular and Small Telescope Asteroids (V < 9.0)

(4) Vesta

Vesta is the brightest asteroid in the Main Belt. This is due to its high albedo (or reflectivity) which causes it to reflect ~42% of the light that strikes it. Vesta is also 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 has dimensions of 347x336x275 miles or 578×560×458 km.

The maps below were created from images taken with the Hubble Space Telescope. The geography is dominated by a large impact crater located near the south pole (the blue ‘donut’ in the elevation map). Perhaps this crater is the result of the impact that blasted off the smaller V-type asteroids. We’ll know more next year when NASA’s Dawn spacecraft enters orbit around Vesta for a full year. Currently the encounter is scheduled for July 2011 to July 2012.

Images and models of the shape of asteroid (4) Vesta. In the upper left is a real HST image, to the upper right is a model of Vesta’s shape, and on the bottom is an elevation map . Credit: NASA/STScI.

Vesta starts the month at magnitude 6.8 and steadily fades to mag 7.3. A small pair of binoculars will allow you to see Vesta among the stars in the “Sickle” of Leo.

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

(2) Pallas

Pallas is a dark 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 similar in size to Vesta with dimensions of 350x334x301 miles or 582x556x501 km. The reason it is fainter than Vesta is its darker albedo of 16%. Though no spacecraft are scheduled to visit Pallas, Hubble was able to get some good images that clearly show its nearly spherical shape.

HST Image of asteroid (2) Pallas. Credit: NASA/STScI.

This month it brightens from magnitude 8.7 to a peak of 8.6 at opposition on April 20. By month’s end, Pallas is back down to magnitude 8.7. Over the course of the month as it travels north through the constellation of Serpens.

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.

In The Sky This Month – March 2010

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of March 2010. Mars is still the dominant planetary object in the evening sky though it it being joined by Venus in the early evening hours and Saturn in the late evening.

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

Planets

Mercury – The innermost planet spends most of the month too close to the Sun for most observers. During the last week of the month, Mercury quickly climbs out of the evening twilight sky on its way to its best evening apparition of the year in early April. By the end of March it can be found a few degrees to the lower right of Venus.

Venus – Here in Tucson, Venus is relatively easy to see thanks to our clear sky and lack of obscuring trees. For most people, the planet is still a difficult sight requiring a clear western horizon. At the start of the month, it sets a little less than an hour after the Sun. This gap grows to ~1.6 hours by the end of March. Not to worry though, Venus will be much higher and easier to see over the next few months. For northern observers, it will be highest in June. The best time for southern observers will be August.

Mar 17 - Moon passes 6° from Venus

Mars – Mars was at opposition (the point opposite the Sun in the sky) on January 29. Opposition means Mars is closest to Earth and at its brightest. This month the Earth and Mars continue to move further apart. As a result, Mars will quickly fade from magnitude -0.6 to +0.2. Still it will be a brilliant red beacon high in the eastern sky right after sundown outshining all but the brightest few stars. Note that unlike the stars which twinkle, Mars shines with an unwavering red glow.

Mar 25 - Moon passes close (4°) to Mars

Saturn – Saturn is at opposition in Virgo on March 21 when it will shine at magnitude +0.5. Telescope users should note that Saturn’s rings are still within a few degrees of edge-on.

Mar 2 - Moon and Saturn within 8° of each other

JupiterJupiter is too close to the Sun for most observers. It will once again be visible in the early morning hours next month.

Meteors

March marks the month with the lowest level of meteor activity. The year is usually split in 2 with January through June having low rates with few major showers while July through December (really through the 1st week of January) have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During March, 8-10 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

No major showers this month.

Minor Meteor Showers

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

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

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V = 6.0 – 8.0)

None

Small Telescope Comets (V = 8.0 – 10.0)

Comet 81P/Wild 2

Comet Wild 2 is a short-period Jupiter-family comet on a 6.4 year orbit. In 1974 a close approach to Jupiter placed the comet on its current orbit which allows (relatively) close approaches to the Sun and Earth. Swiss professional astronomer Paul Wild found the comet photographically on its first close perihelion in 1978. During its last perihelion passage it was the target of the NASA Stardust spacecraft which flew through its coma, collected cometary dust, and returned the dust to Earth. Though Wild 2 has become bright enough to be seen in small backyard telescopes before, this year’s apparition will be its best since discovery. Not till 2042 will it come closer, and even then only marginally so.

The nucleus of comet Wild 2 taken by the Stardust spacecraft. Credit: NASA/JPL/Stardust team.

This year Wild 2 reached perihelion on February 22 at 1.60 AU while closest approach to Earth will occur on April 5 at 0.67 AU. Though the comet will only reach a brightness of magnitude ~9.2 to 9.5 in March, it will remain brighter than magnitude 10.0 from January through May. At mid-month the comet a morning object located in Virgo at a distance of 1.61 AU from the Sun and 0.71 AU from Earth.

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

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

Comet C/2009 K5 (McNaught) and C/2009 O2 (Catalina)

These two long-period comets should become brighter than magnitude 10 this month. Both were found by components of the Catalina Sky Survey, one in Australia and the other in Arizona.

Comet McNaught was discovered by Rob McNaught on the night of May 27, 2009 deep in the southern sky. The discovery was made with the 0.5-m Uppsala Schmidt telescope from Australia as part of the Siding Spring Survey (one of the three Catalina Sky Survey components) for unknown asteroids and comets. At the time, the comet was a faint 17th magnitude.

With perihelion on April 30 of this year at a distance of 1.42 AU from the Sun, C/2009 K5 is now bright enough to be seen in small backyard telescopes from dark sites. During the month it should be as bright as 9.0 to 10.0 magnitude as it moves north while paralleling the Milky Way in Aquila. The comet will be a morning object all month long. At mid-month it will be located 1.57 AU from the Sun and 1.67 AU from Earth.

Comet Catalina was first spotted as an asteroidal object by observers at the Catalina Sky Survey proper on July 27, 2009. At the time the comet was 19th magnitude and probably just barely visible in images taken with the 0.68-m Catalina Schmidt telescope.

This comet is currently only 11th magnitude. The comet should rapidly brighten as it approaches its March 24th perihelion at a distance of 0.70 AU from the Sun. At that time the comet may be as bright as magnitude 9.0 as it cruises through the Milky Way constellations of Vulpecula, Cygnus, Lacerta and Andromeda in the morning sky.

Asteroids

Binocular and Small Telescope Asteroids (V < 9.0)

(4) Vesta

Vesta is the brightest asteroid in the Main Belt. This is due to its high albedo (or reflectivity) which causes it to reflect ~42% of the light that strikes it. Vesta is also 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 has dimensions of 347x336x275 miles or 578×560×458 km.

The maps below were created from images taken with the Hubble Space Telescope. The geography is dominated by a large impact crater located near the south pole (the blue ‘donut’ in the elevation map). Perhaps this crater is the result of the impact that blasted off the smaller V-type asteroids. We’ll know more next year when NASA’s Dawn spacecraft enters orbit around Vesta for a full year. Currently the encounter is scheduled for July 2011 to July 2012.

Images and models of the shape of asteroid (4) Vesta. In the upper left is a real HST image, to the upper right is a model of Vesta's shape, and on the bottom is an elevation map . Credit: NASA/STScI.

Vesta starts the month at magnitude 6.2 and steadily fades to mag 6.8. Sixth magnitude is close to the brightest Vesta can get and is easy for binocular observers. If you are lucky enough to be located in a very dark rural site you may even be able to see Vesta by naked eye among the stars in the ‘sickle’ of Leo.

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

(532) Herculina

Herculina is a stoney S-type asteroid with a run-of-the-mill albedo of 16%. Though one of the brightest asteroids in the Main Belt, it avoided discovery for a century after the first asteroids were found (being found in 1904). As a result, this is the highest numbered asteroid that is relatively easy to see with a backyard telescope.

In March Herculina is at opposition and is between magnitude 8.8 and 9.0 for the entire month as it travels among the stars of Coma Berenices.

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.

(2) Pallas

Pallas is a dark 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 similar in size to Vesta with dimensions of 350x334x301 miles or 582x556x501 km. The reason it is fainter than Vesta is its darker albedo of 16%. Though no spacecraft are scheduled to visit Pallas, Hubble was able to get some good images that clearly show its nearly spherical shape.

HST Image of asteroid (2) Pallas. Credit: NASA/STScI.

This month it brightens from  magnitude 9.0 to 8.7 over the course of the month as it travels north through the constellation of Serpens.

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.

In The Sky This Month – 2009 April

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

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

Planets

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

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

mercury_moon_apr26
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.

saturn_20090328_1007_lunsford
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.

venus_moon_mars_april22
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.

yi-swan4

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

Comet C/2007 N3 (Lulin)

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

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

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

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

Comet C/2006 W3 (Christensen)

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

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

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

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

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

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

Asteroids

Binocular and Small Telescope Asteroids (V < 10.0)

(1) Ceres

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

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

(2) Pallas

Pallas is also a carbonaceous asteroid though with a slightly bluish B-type spectrum. Due to its high inclination (tilt of its orbit with respect to Earth’s orbit) of 34 degrees it is a difficult target for future spacecraft missions. Pallas is large with dimensions of 350x334x301 miles or 582x556x501 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 136x136x113 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

In The Sky This Month – March 2009

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

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

Planets

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

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.

saturn_allsky_09452
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.

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

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

Meteors

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

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During November, six (6) or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

None.

Minor Meteor Showers

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

Delta Leonids (DLE)

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

Gamma Normids (GNO)

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

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

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

Comets

Naked Eye Comets (V < 6.0)

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

Binocular Comets (V < 8.0)

Comet C/2007 N3 (Lulin)

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

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

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

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

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

Small Telescope Comets (V < 10.0)

Comet C/2006 W3 (Christensen)

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

The comet is currently around magnitude 9.7 and will slowly brighten during the month.  It is moving near the border of Lacerta and Pegasus.  The comet is best seen in the early morning. I was able to observe the comet visually with my backyard 12″ reflecting telescope in November. Being small and condensed, the comet was fairly easy to see.

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

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

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

Comet 144P/Kushida

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

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

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

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

Asteroids

Binocular and Small Telescope Asteroids (V < 10.0)

(1) Ceres

Ceres is the biggest asteroid in the Main Belt with a diameter of 585 miles or 975 km. It is so big that it is now considered a Dwarf Planet. Classified as a carbonaceous (carbon-rich) Cg-type asteroid, there are suggestions that it may be rich in volatile material such as water. Some even propose that an ocean exists below its surface. Ceres is one of two targets for NASA’s Dawn spacecraft which is scheduled to visit it in 2015. Last month Ceres was at opposition (at its closest to the Earth and at its brightest). This month Ceres will fade from from magnitude 6.9 to 7.4 as it moves into Leo Minor, just north of Leo. If you are observing Saturn with a telescope or pair of binoculars, try your hand at finding Ceres with one of the finder charts linked below.

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

(2) Pallas

Pallas is also a carbonaceous asteroid though with a slightly bluish B-type spectrum. Due to its high inclination (tilt of its orbit with respect to Earth’s orbit) of 34 degrees it is a difficult target for future spacecraft missions. Pallas is large with dimensions of 350x334x301 miles or 582x556x501 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 347x336x275 miles or 578×560×458 km. Vesta will also be visited by NASA’s Dawn spacecraft which will arrive in 2010. On October 30, Vesta was at opposition (directly opposite from the Sun in the sky) and at its brightest. This month Vesta is an evening object moving through Aries before entering Taurus near the end of the month. It will fade from magnitude 8.3 to 8.5.

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

(14) Irene

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

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

(27) Euterpe

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

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

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

(29) Amphitrite

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

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

In the Sky This Month – January 2009

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.

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)

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)

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

The comet is currently around magnitude 10.2 and will slowly brighten during the month.  It will be traveling south through the 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

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 in Leo brightening from magnitude 7.9to 7.2.

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 350x334x301 miles or 582x556x501 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 347x336x275 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.

In The Sky This Month – November 2008

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.

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

Comets

Naked Eye Comets

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

Binocular Comets

Comet C/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 350x334x301 miles or 582x556x501 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 347x336x275 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 140x120x85 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.