In the Sky This Month – July 2009

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of July 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 quickly drops out of view in the morning sky as the month starts. After superior conjunction (passing the Sun on its far side) on July 14, Mercury again starts to become visible low in the WNW in the evening. This apparition which is best in Aug/Sept will be great from the Southern Hemisphere but very poor from the Northern.

Saturn – Saturn is still the easiest planet to observe during the evening this month. By the end of twilight, Saturn is in the southwest under the eastern part of the constellation of Leo.

This year Saturn is dimmer than usual. At magnitude +1.0 to +1.1, 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.

Ring plane crossings occur once every half-Saturnian year (~15 years). Though the rings are over 70,000 kilometers (43,500 miles) wide, they are only 10 meters (33 feet) thick. Since the rings are seen edge, or width, on during ring plane crossings, they can actually appear to disappear in most telescopes. The last time this happened was in 1995. This year the crossing happens on Sept 4 when Saturn is too close to the Sun to be observed. Still, the rings will appear very narrow and line-like this month.

The 3-day old crescent Moon will pass a relatively distant 6 degrees to the south of Saturn on the evening of July 24.

Image of Saturn by Bob Lunsford from early May 2009.

Jupiter and Neptune - Jupiter rises late in the evening and is highest in the sky an hour or so after midnight. Other than Venus, it is the brightest “star” at dawn with a  magnitude of -2.7 to -2.8. 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 -2.7 to -2.8 while Neptune will be a faint +7.8. That makes Jupiter over ~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. The Moon will pass within 3 degrees of both planets on the morning of July 10.

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

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

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).

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 start the month within 4 degrees of each. By month’s end, the pair will be 16 degrees apart. Mars will continue to slowly brighten and become better placed for observation as the year progresses.

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

Meteors

July marks a large uptick in the 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 June, 12 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

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

The Southern δ-Aquarid shower is the only major shower of July producing from 10-20 meteors per hour at their peak. They are part of the Machholz complex of asteroids, comets and meteor showers that are the result of the breakup of a single comet into hundreds of smaller objects over the past thousands of years. The complex includes comet 96P/Machholz, the suspected extinct comet 2003 EH1, hundreds of Marsden and Kracht group comets, and the Quadrantid and Arietid meteor showers.

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

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

Minor Meteor Showers

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

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

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

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

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

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

The Perseids are one of the best meteor showers of the year and never disappoint… in August. During July, the shower is a consistent producer of a small number of showers as it slowly builds toward its August 12 peak. Expect to see a meteor or 2 per hour from the Perseids during the 2nd half of July. This is way short of the 60-120 meteors per hour that can be seen at its peak though this year the near Full Moon will cut down on those rates.

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 7.0. With perihelion this month, the comet should be as bright as it gets though one never knows with outburst comets.

The comet is now visible from both Hemispheres. It travels northward from Corvus into Virgo in the evening sky.

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

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

Small Telescope Comets (V = 8.0 – 10.0)

Comet C/2006 W3 (Christensen)

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

The comet is currently around magnitude 8.5 and should be at its brightest this month.  It is moving near the border of Pegasus and Cygnus.  The comet is best seen after 10 pm.

The comet will reach perihelion at a rather distant 3.12 AU from the Sun on 2009 July 6. 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/2008 T2 (Cardinal)

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

At perihelion on June 13th, the comet passed within 1.20 AU of the Sun. The comet can only be seen from the Southern Hemisphere as it is located south of the Sun. The comet is currently magnitude 8.5 to 9.0 as it moves southeast from Canis Minor into Antilia in the evening sky. It is too bad the comet is located so far from Earth. At a distance of 1.8 AU from Earth, it is located on the other side of the Sun. If this comet has approached as close as Comet Lulin (0.4 AU) did, Comet Cardinal would be shining at 5th magnitude and be visible to the naked eye from dark locations.

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

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

22P/Kopff

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

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

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

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

Asteroids

Binocular and Small Telescope Asteroids (V < 10.0)

(3) Juno

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

This month it will be moving slowly eastward through Pisces while brightening from magnitude 9.7 to 9.1. Peak brightness will come at opposition on Sept. 22 when Juno will be as bright as magnitude 7.6. A few degrees to the eats of Juno is another bright asteroid, (18) Melpomene which is described in its own section.

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

(7) Iris

Iris is an inner Main-Belt asteroid that can occasionally get as bright as any asteroid. This year, Iris 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 July, it is located in the constellation of Sagittarius at magnitude 8.8 at the start of the month and magnitude 9.3 at the end. On the nights of July 23/24/25 UT, Iris will pass in front of the bright open star cluster M25 for a nice photo-op.

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

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

(18) Melpomene

Just a few degrees to the east of (3) Juno lies another nice asteroid target for small telescopes. (18) Melpomene is also located in the constellation of Pisces and is only a little bit fainter than Juno, brightening from magnitude 10.0 to 9.4 in July.

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

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

In The Sky This Month – June 2009

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

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

Planets

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

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

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

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

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

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

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

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

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

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

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

Meteors

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

Sporadic Meteors

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

Major Meteor Showers

None

Minor Meteor Showers

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

June Bootids (JBO)

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

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

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V = 6.0 – 8.0)

Comet C/2008 Q3 (Garradd)

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

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

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

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

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

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

Small Telescope Comets (V = 8.0 – 10.0)

Comet C/2008 T2 (Cardinal)

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

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

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

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

Comet C/2006 W3 (Christensen)

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

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

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

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

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

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

Comet C/2009 G1 (STEREO)

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

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

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

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

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

22P/Kopff

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

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

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

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

Asteroids

Binocular and Small Telescope Asteroids (V < 10.0)

(1) Ceres

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

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

(7) Iris

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

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

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

In The Sky This Month – May 2009

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

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

Planets

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

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

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

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

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

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

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

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

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

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

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

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

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

Meteors

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

Sporadic Meteors

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

Major Meteor Showers

Eta Aquarids (ETA)

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

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

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

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

Minor Meteor Showers

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

Eta Lyrids (ELY)

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

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

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V < 8.0)

None

Small Telescope Comets (V < 10.0)

Comet C/2009 F6 (Yi-SWAN)

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

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

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

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

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

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

Comet C/2008 Q3 (Garradd)

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

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

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

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

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

Comet C/2006 W3 (Christensen)

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

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

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

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

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

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

Comet C/2009 G1 (STEREO)

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

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

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

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

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

Comet C/2009 E1 (Itagaki)

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

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

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

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

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

Comet C/2008 T2 (Cardinal)

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

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

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

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

Asteroids

Binocular and Small Telescope Asteroids (V < 10.0)

(1) Ceres

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

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

(8) Flora and (14) Irene

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

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

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

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