This is the Dudley Observatory Skywatch Line for Wednesday, September 30th and Thursday, October 1st written by Louis Suarato
The 88%, illuminated waning gibbous Moon rises at 8:17 p.m. Wednesday night. Rising 15 degrees to the Moon’s northeast will be the Pleiades star cluster. Thursday night, the Moon will below the Pleiades and about 5 degrees to Aldebaran’s upper right. Further to the northeast will be the constellation Auriga’s brightest star, Capella. Capella is the 6th brightest star in the sky and the third brightest in the northern celestial hemisphere. It is also the brightest yellow star that can been seen in our sky. Capella is the nearest to the Pole of all 1st magnitude stars. Capella, also known as Alpha Aurigae, is a multiple star system consisting of a pair of binary stars. The brightest pair consists of two stars with radii 10 times larger than our Sun. These two giant stars have been designated as Capella Aa and Capella Ab. These two bright giant stars orbit each other once every 104 days. Their faint companions are known as Capella H and Capella L. This multiple star system is estimated to be 42.8 light-years from Earth.
To the lower right of Capella are three open star clusters. The nearest is M38, or The Starfish Cluster. Discovered by Le Gentil in 1749, M38 has over 100 stars within its cluster. Approximately 2.3 degrees to M38’s southeast is the open cluster, M36, also designated NGC 1960. M36 and M38 can be seen in the same field of view of a low-power, wide angle telescope. M36 is the smaller of the two clusters, but brighter, containing about 60 stars of magnitudes 9 to 14. The open star cluster M37, or NGC 2099, is located about 3 degrees below M36. C.E. Barns described M37 as a “diamond sunburst”. M37 was discovered by Giovanni Batista Hodierna before 1654 and contains about 60 stars.
Thursday’s pre-dawn sky features the planets Venus, Mars and Jupiter rising over the eastern horizon. Leo’s brightest star, Regulus, will be found below Venus and above Mars. Continue to follow these planets during October as they draw closer.