The March Skywatch: Another Comet


Even as I have begun to tell you about the possible best comet sighting in 100 years, that astronomers are telling us may happen in November and December this year (2013), we suddenly find a foretaste of that event will be here and visible to us in March! Another Comet of potential significant naked-eye brightness is coming this month.

Comet C/2011 L4(PANSTARRS) reaches it closest point to the Sun (perihelion) on March 9th (Saturday), when it lies 28 million miles from our star. If astronomer’s predictions hold true it should be around magnitude 0.0 or –1.0 then. On March 12th, looking due west, 30 minutes after sunset, we should see a slender crescent Moon just 8 degrees above the horizon, with the comet’s head, or coma, 4 degrees to the left of the Moon. Really to see it then will require twilight to deepen, and we will probably need binoculars to find it. But finally, as the sky darkens, the comet’s dusty tail should come into view. March 13th, the waxing crescent Moon will lie in line with any potential long tail the comet may develop.

During the next 6 to 8 days, Comet PANSTARRS will appear to move to the northwest, heading toward Cassiopeia and eventually the Little Dipper, and fade in brightness. It should however, remain near first magnitude star brightness until March 20th. By the first of April it dims to +3.0, and by May 1st is down to +6 or +7. This brief comet view is a nice warm-up for the big one at the end of the year. Comet C/2012 S1 (ISON) is 10,000 times as bright as Comet PANSTARRS! But in itself, it should be well worth observing from March 9 through March 23rd.

Jupiter and Saturn are the only two planets visible this month, with Jupiter, the brighter of the two, at –2.3 magnitude, clearly seen among the stars of Taurus up in the southwestern sky until setting around 1 am. Saturn rises around midnight this month and becomes prominent in the East by 2 am and remains so until dawn. It is found among the stars of Libra, about 20 degrees east of Spica, the brightest star in Virgo. Another great conjunction of the Moon and Jupiter will occur this month on the night of March 17th, when the crescent Moon will be seen just a degree and a half below the giant planet.

We reach Vernal Equinox on March 20th (7:02 am EDT) — the so-called 1st day of spring, when the Earth’s tilt is such that both the Northern and the Southern Hemispheres receive equal amounts of the Sun’s light, and day and night length equal 12 hours each. From then until Summer Solstice, day length will grow and night-time will grow shorter, and the atmosphere and the Earth in the north will warm into spring and summer.

Full Moon in March is March 27th; and New Moon is on the 11th. 1st quarter is March 19th, while Last quarter is March 4th. By the way; the Comet this month gets its name from its discoverers, a team of astronomers at the University of Hawaii. Pan-STARRS is an acronym for the Panoramic Survey Telescope and Rapid Response System — an innovative design for a wide-field imaging facility at the University of Hawaii. It combines a 1.8 meter mirror telescope with a 1.4 gigapixel digital camera to conduct research programs in space observations and surveys.

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