This is Dudley Observatory’s Skywatch Line for Friday, September 24, through Sunday, September 26, written by Sam Salem.
On Friday, Sun rises at 6:45am and sets at 6:48pm; Moon sets at 10:18am and rises at 8:43pm.
On Friday morning, watch the Moon sitting below the magnitude 5.7 Uranus in the west-southwestern sky. When they rise again on Friday night, the Moon will sit 5 degrees to Uranus’ lower left, close enough for them to share the view in binoculars. The blue-green dot of Uranus can be seen in binoculars. Note Uranus’ location between the stars of the constellations of Aries and Cetus and seek it out on the weekend when the bright Moon will have moved away from it.
Late at night on Saturday and Sunday, watch as the waning gibbous Moon sweeps in front of the constellation Taurus the Bull. The bright Moon might make it tough to see the starlit figure of the Bull on these nights. But you should be able to make out Aldebaran, Taurus’ brightest star, as well as the tiny, misty, dipper-shaped Pleiades star cluster, also known as Messier 45, the Seven Sisters, Subaru, and Matariki. When the Moon moves away, look for the V-shaped Face of the Bull itself. When the waning gibbous Moon rises in mid-evening on Saturday, it will shine several finger widths below the bright Pleiades star cluster. The broad Hyades star cluster that forms the triangular face of Taurus the bull will be located below the Moon. The Moon and the Pleiades will share the field of view of binoculars. By dawn, the rotation of the sky will lift the Hyades to the left of the Pleiades, with the Moon midway between them.
Venus, brilliant at magnitude –4.1, shines low in the west-southwest during twilight. It sets around twilight’s end. Jupiter, at magnitude -2.8, and Saturn, at magnitude +0.4, shine in the southeast to south during evening. They are 16 degrees apart on opposite sides of dim constellation Capricornus. During twilight bright Jupiter, on the left, is slightly the lower of the two. They level out not long after dark, and later they tilt the other way, with Saturn now the lower one. Saturn sets around 3 a.m. followed down by Jupiter about an hour later.
Bright Arcturus, pale yellow-orange, shines ever lower in the west-northwest after dark. The narrow kite shape of its constellation, Boötes, extends two fists at arm’s length to Arcturus’s upper right. Arcturus is where the kite’s downward-hanging tail is tied on. To the right of the top of the kite, the Big Dipper is turning more level. This is the time of year when, during the evening, the dim Little Dipper “dumps water” into the bowl of the Big Dipper way down below.
Cygnus the Swan floats just about straight overhead these evenings. Its brightest stars form the big Northern Cross. When you face southwest and crane your head way, way up, the cross appears to stand upright. vIt’s about two fists at arm’s length tall, with Deneb as its top.
The Moon won’t rise now until about an hour after dark on Saturday night. If you have a dark sky, take this opportunity to look for the Milky Way running straight up from the west-southwest horizon, along the backbone of Aquila and to the just right of bright Altair high in the south, along the shaft of the Northern Cross overhead, and straight down through Cassiopeia and northern Perseus to the east-northeast horizon.