Skywatch Line for Wednesday and Thursday, August 9 and 10, 2023
This is Dudley Observatory’s Skywatch Line for Wednesday and Thursday, August 9 and 10, written by Alan French.
The Sun rises at 5:55 A.M. on Wednesday and sets at 8:06 P.M. On Thursday it rises at 5:56 and sets at 8:05. This Thursday has 16 ½ minutes less daylight than last Thursday.
The Moon was at last quarter Tuesday morning and is now headed toward new. If ou’re up before sunrise on Thursday morning look for a crescent Moon toward the east. At 5:00 A.M. it will be 30% in sunlight. Friday morning it will be just over 24% illuminated. It will reach new on Wednesday, August 16.
If you are enjoying the crescent Moon in the morning sky at 5:00 A.M., look for bright Jupiter high in the southeast. Jupiter now shines at magnitude -2.5 and is 56 degrees above the southeastern horizon at 5:00 A.M.
By 10:00 P.M. Sagittarius, the Archer, is almost due south and well placed under dark, moonless skies. The brighter stars of Sagittarius outline a very nice teapot shape, with the tip of its top lying 21 degrees above the horizon. Four stars below the top outline the pot, which widens toward the bottom. Two more stars to the east (left) add a handle, and one to the west (right) completes the spout. The pot is tipped slightly downward toward the west.
If you are enjoying the night sky away from city lights and the skies are dark, the Milky Way looks like steam rising from the teapot’s spout, heading upward and somewhat behind the pot.
The tip of the teapot is a fine landmark for finding a celestial gem, the globular cluster M-22. Globular clusters are huge balls of stars, and M-22 is one of the finest and the brightest visible from our northern latitude. At magnitude 5.6 it can be spotted by eye under dark skies, appearing as a fuzzy star. It lies 2 ½ degrees to the upper left of Kaus Borealis, the star marking the tip of the teapot. (Remember that
the pinkie, held at arm’s length, spans 1 degree across its tip.) M-22 is an easier, better sight in binoculars, which will also reveal it if it eludes the eye alone. It is a beautiful sight, and a favorite of amateur astronomers, through a telescope. It is now due south, highest, and best seen at 10:20 P.M.
M-22 is one of the closest globular clusters, lying 10,600 light years away. It is 99 light years in diameter.
The designation M-22 means this globular cluster is number 22 on a list kept by observer and comet hunter Charles Messier. The list includes a variety of “Deep Sky Objects,” star clusters, nebulae, and galaxies Messier encountered while exploring the sky. The modern version of the list includes 110 objects and many of the best telescopic sights in the night sky. Beginning telescope users often observe all the objects on Messier’s list.