Stars over Sisters

March is a good month to try to identify Cancer the crab, the zodiac's dimmest constellation. It helps an observer to know that Cancer is bordered by two brighter constellations, Gemini to the west and Leo to the east. Situated about halfway between the stars Pollux in Gemini and Regulus in Leo is a dim, fuzzy object that is just visible to the naked eye in dark skies. This body, called Praesepe, was discovered to be a star cluster when Galileo viewed it with his telescope in 1609. Also known as the beehive cluster, it is comprised of about a thousand stars.

Located about nine degrees north of Praesepe is Iota Cancri, considered to be one of the finest double stars in the heavens. The strongly contrasting yellow and blue colors of the two stars make this a beautiful pair, and it's resolvable even in small telescopes.

According to Greek mythology Hera, Zeus' wife, sent Cancer (also known as Karkinos), to distract Hercules in his battle with Hydra, the multi-headed sea monster. But when Karkinos grabbed onto Hercules' toe with its claws, the Hero simply crushed the crab underfoot. However, other cultures believed Cancer to be the great gate through which souls came to earth from heaven, after which they would be born into human bodies.

The first of two potentially bright comets that will appear in 2013 is due this month. Journeying sunward from the outer regions of the solar system, PANSTARRS C/2011 L4 will be closest to the earth on March 5, then nearest the sun on March 10. Although recent observations indicate the comet may not be quite as bright as originally predicted, it still should be easily visible to the naked eye. Look for it low in the west at dusk after March 10.

Spring begins at 4:02 a.m. PDT on March 20. At that time the sun will reach the vernal equinox and lie directly overhead at the equator. This results in nearly equal hours of day and night at most locations on the earth.

Jupiter, the largest planet in the solar system, is still the brightest object in the evening sky. It is high in the west at nightfall and sets at about 1:30 a.m. by mid-month. The ringed planet Saturn is currently in the constellation of Libra and by month's end will rise in the east by about 9:50 p.m. Mercury will be aligned directly between the earth and the sun on March 4 and becomes a morning object late in the month. Neither Venus nor Mars are visible because they're on the other side of the sun from the earth.

The new moon occurs on March 11, providing a few days of dark skies in which to view the comet. Thereafter the moon waxes, becoming full on March 27.