This is the Dudley Observatory Skywatch Line for Wednesday, May 2nd, and Thursday, May 3rd, written by Louis Suarato.
The 94% illuminated, waning gibbous Moon sets at 7:49 a.m. Wednesday, and rises again at 10:40 p.m. in the constellation Ophiuchus. Ophiuchus is the 11th largest constellation, visible in the evening sky from May through September. This dim constellation crosses the celestial equator, the ecliptic, and the Milky Way. It is the only constellation that crosses the ecliptic, and is not a member of the zodiac. The brightest star in Ophiuchus is Ras Alhague, shining at magnitude 2.1. Ophiuchus is the home of the Summer Beehive Cluster, and globular clusters, M10 and M12. Located right of center of the constellation, M10 was discovered by Charles Messier on May 29, 1764. At 7th magnitude, this globular cluster is 83 light-years across and is estimated to be 14,300 light-years away. Look about 3 degrees above M10 for globular cluster M12. M12 is a bit fainter, and slightly larger than M10. Discovered by Messier one day after he discovered M10, M12 contains approximately 200,000 stars.
Jupiter precedes moonrise, appearing over the southeastern horizon at 8:23 p.m. in Libra. Thursday night, at 4 minutes before midnight, Europa is eclipsed by Jupiter’s shadow. Europa will reappear at 2:22 a.m. Friday. Saturn rises at 23 minutes past midnight in Sagittarius, less than 2 degrees above globular cluster M22. One of the brightest globular clusters in the sky, M22’s stars peak at 11th magnitude, with the cluster itself, shining at magnitude 5.10. Discovered by Abraham Ihle on August 26, 1665, M22 is one of the nearer globular clusters, at an approximate distance of 10,600 light-years. Located near the galactic center, and only 2.5 degrees away from the Teapot asterism’s top star, Kaus Borealis, M22 is estimated to be 12 billion years old, and contains 83,000 stars. Mars follows Saturn, rising about an hour later. Mars will move from Sagittarius to Capricornus at mid-month. Look over the west-southwestern horizon after sunset, where Venus and Taurus’ brightest star, Aldebaran, will be separated by 7 degrees.. Look for the Pleiades star cluster to their right.