This is the Dudley Observatory Skywatch Line for Wednesday, December 6th, and Thursday, December 7th, written by Louis Suarato.
The 88% illuminated, waning gibbous Moon sets at 9:50 a.m., and rises again 85% illuminated at 7:50 Wednesday night in the constellation Cancer. Look to the lower left of the Moon with binoculars to see M44, the Beehive Cluster. At a diameter of 1.5 degrees, the Beehive Cluster is 3 times the width of the Full Moon. M44 is an open star cluster consisting of approximately 1,000 stars. At 520 to 610 light-years away, the Beehive Cluster is one of the nearest star clusters. On other nights, you can find the Beehive Cluster by looking between Leo’s brightest star, Regulus, and Gemini’s two brightest stars, Castor and Pollux. Saturn and Mercury are 1.2 degrees apart 40 minutes after sunset, but may be too low on the west-southwestern horizon to see. Mars rises in Virgo at 3:15 a.m., followed an hour and 10 minutes later by Jupiter. Mars is currently 2.159 astronomical units from Earth, or 200.7 million miles. Jupiter is currently 6.23 astronomical units, or 579.1 million miles from Earth. Between the vast distance of these two outer planets is the Asteroid Belt. The Asteroid Belt is made up of tens of thousands of space rubble that are too small to be considered planets. About half of the mass of the asteroid belt is comprised of the largest of these minor planets, which are Ceres, Vesta, Pallas, and Hygeia. Ceres, with a diameter of 587 miles, has a mass of about a third of the Asteroid Belt’s total mass. Ceres, at magnitude 7.93, can be found about 8 degrees west of the star at the end of the head of Leo, known as Algenubi. If the mass of all asteroids were combined, it would still be less than that of Earth’s Moon.