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.

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