In the Transient Sky – March 2012

Well, I guess this month’s “In the Transient Sky” is better late than never. This month is definitely the “Month of the Planets” in the evening sky. During the beginning of the month, 4 planets are visible (Mercury, Venus, Jupiter and Mars) with a 5th (Saturn) rising later in the evening.

March 2012 Highlights
* Venus and Jupiter have a spectacular conjunction in the SW
* Mars reaches opposition and peak brightness
* Comet C/2009 P1 (Garradd) is a nice circumpolar binocular object

Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <>.


Evening Planets

Mercury – Mercury starts the month near its maximum elongation in the western evening sky about ~25° to the lower right of much brighter Venus. By the 10th, the innermost planet is diving back into the Sun’s glare. Observers with a clear view of the western horizon may be able to follow Mercury till about the 12th or 13th. Next month it will begin a very poor (for Northern Hemisphere observers) morning apparition. The next Evening apparition will be in June/July.

Venus and Jupiter – Venus is the brilliant beacon in the southwest after sunset. At the end of the month (Mar 27) Venus will be at its highest in the twilight sky. It won’t be at its  brightest will the end of April (Apr 30). The real showstopper occurs at the end of the apparition in June when Venus will transit the disk of the Sun. This will be the last Venus transit till 2117. The Moon and Venus make a gorgeous pair on the evening of the 25th.

Jupiter, the King of Planets, closely shares the evening sky with Venus. By the 10th, the two are located within 4° of each other (8 lunar diameters). They close to within 3° (or 6 lunar diameters) of each other on March 13. Jupiter will continue to fall behind Venus and by month’s end the two will be ~15° apart.

The Moon makes a beautiful pairing with Jupiter on the 25th and Venus on the 26th.

Mars – After admiring Venus and Jupiter, turn around 180° and take a look for Mars, the bright reddish “star” in the East after evening twilight. Mars reached opposition the point opposite the Sun on the sky) on March 3 and is closest to Earth on March 5 at a distance of 0.674 AU or just under 63 million miles (~101 million km). Since Mars was near its aphelion when we passed it on our inside track, this opposition is almost as faint as can be at a magnitude of -1.2. The red planet will spend the rest of the month slowly fading and retrograding towards Regulus in the constellation of Leo.

Morning Planets

Saturn – Kind of the forgotten planet this month is Saturn. At magnitude +0.4 to 0.3 Saturn is located a few degrees to the lower left of the slightly fainter star Spica in Virgo (magnitude +1.0). On the 10th, the ringed planet gets high enough above the eastern horizon for easy observing by 10pm. At the end of the month, Saturn is easily seen around 9pm. The Moon visits on the morning of the 10th and 11th.


The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers. March marks the lowest rates of the year.

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 January mornings, 10 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

None this month.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are 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 International Meteor Organization’s 2012 Meteor Shower Calendar.


Naked Eye Comets (V < 6.0)

None this month.

Binocular Comets (V = 6.0 – 8.0)

C/2009 P1 (Garradd)

First seen way back on August 13, 2009 by Gordon Garradd who was observing for the Siding Spring Survey, a NASA-funded survey observing from Australia. At the time of discovery it was located at a distance 8.7 AU from the Sun, nearly the distance of Saturn. Perihelion occurred 2 days before Christmas 2011 at 1.55 AU from the Sun. Though the comet does not get very close to the Sun, it is an intrinsically bright comet and could have been a real sight had it come closer to the Sun and Earth.

The comet is in full retreat from the Earth and Sun this month as it is at the beginning of a long journey back to the cold depths of the outer Solar System. At mid-month it is 1.91 AU from the Sun and 1.30 AU from Earth and by month’s end it will be 2.04 and 1.50 AU from the Sun and Earth, respectively.

Comet Garradd is now a circumpolar object for the Northern Hemisphere meaning it never sets for those of us at Northern mid-latitudes and further north. Racing away from Ursa Minor, the comet will pass to the north and west of the Big Dipper through the “head” of Ursa Major. Since the comet is moving away from us and the Sun it should finally begin to fade from around magnitude 6.8 to 7.7 as the month progresses.

Date       RA       DEC     Delta    r    Elong   Mag
Mar  1   15h 24m  +65°59'   1.272  1.809   106    6.8
Mar 10   13h 23m  +70°35'   1.275  1.873   111    7.0
Mar 20   10h 59m  +67°32'   1.346  1.949   112    7.2
Mar 31   09h 39m  +58°51'   1.500  2.038   108    7.7

Small Telescope Comets (V = 8.0 – 10.0)


About Carl Hergenrother
I am a professional astronomer specializing in the study of comets, asteroids and meteors. This blog will focus on my professional and amateur work in this field

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