Skywatch Line for Friday, March 27, through Sunday, March 29, written by Sam Salem
This is Dudley Observatory’s Skywatch Line for Friday, March 27, through Sunday, March 29, written by Sam Salem.
On Friday, Sun rises at 6:46am and sets at 7:16pm; Moon sets at 4:11am and rises at 1:23pm.
The Moon passes near the outskirts of the Beehive Cluster, M44, on Friday night. M44 sits just southeast of the Moon. The center of the cluster is less than 2° from the Moon. Binoculars or a small telescope shows both in the same field of view, although the bright Moon will wash out fainter cluster stars. The Beehive covers an area about 95’ across, about three times the width of the Full Moon. It is easily visible with unaided eyes, although the nearby Moon will hinder the view without optical aid. Around midnight, the Moon sits due north of the Beehive’s center.
On Saturday and Sunday evenings, the waxing gibbous Moon will be near Regulus, the brightest star in Leo the Lion. On Sunday, Regulus is only 0.3° south of the Moon. Regulus is the bright dot at the bottom of a backward question-mark pattern of stars known as the Sickle.
Venus, at magnitude –3.9, shines low in twilight Look for it due west as twilight fades. Forty minutes after sunset it will still be about a fist at arm’s length above horizontal. It sets at twilight’s end.
Jupiter, at magnitude –2.2, sits nearly overhead when you face south as the stars come out. Jupiter soon shifts to the very high southwest, then moves lower as the evening grows late. It sets around 2 am on the west-northwest horizon. In a telescope Jupiter is 40 arcseconds wide. It’s shrinking and fading as Earth pulls farther ahead of it in our faster orbit around the Sun.
Cassiopeia is the fall and winter constellation. Look for it fairly low in the north-northwest as it retreats down after dark. It’s standing roughly on its brighter end. For mid-northern latitudes and farther north, Cassiopeia is circumpolar constellation, it never goes away completely. By 2 am it will be at its lowest due north, lying like a W that’s not quite horizontal.
This weekend marks the anniversary of discovery of the second and the fourth asteroids Pallas and Vesta. Pallas was discovered on March 28, 1802. Five year later, Vesta was discovered on March 29, 1807. The German astronomer, Heinrich Olbers, found a convenient method of calculating the orbit of comets that led to these two discoveries.
When Pallas was discovered on 28 March 1802, it was considered to be a planet as were other asteroids in the early 19th century. The discovery of many more asteroids after 1845 led to the separate listing of “minor” planets from “major” planets. The realization in the 1950s that such small bodies did not form in the same way as other planets led to the gradual rejection of the term “minor planet” in favor of “asteroid”, or “planetoid”, for larger bodies such as Pallas.