Skywatch Line for Friday, September 12, through Sunday, September 14, written by Sam Salem
This is Dudley Observatory’s Skywatch Line for Friday, September 12, through Sunday, September 14, written by Sam Salem.
On Friday, Sun rises at 6:32am and sets at 7:10pm; Moon sets at 12:39pm and rises at 9:38pm.
The waning gibbous Moon will pass the Pleiades star cluster on Friday and Saturday mornings. Aldebaran, the brightest star in the constellation of Taurus the Bull, sits nearby. Follow them from late the night before through dawn. Cover the Moon with your finger to make delicate stars near it easier to see.
On Saturday night, the last-quarter Moon rises around 11pm. It forms an isosceles triangle with Capella, the brightest star in the constellation of Auriga the Charioteer, and the open star cluster Pleiades. Capella sits two fists to the Moon’s upper right, and the Pleiades sits at the same distance to its upper left. A little less far to the Moon’s right is Aldebaran.
Last quarter Moon occurs at 6:33am on Sunday morning. It’ll rise after midnight and set around noon. Look for it high in the sky before dawn.
Mercury will lie on the far side of the Sun on Saturday, reaching the point in its orbit known as superior conjunction.
Venus and Jupiter shine in the east before and during dawn, low at magnitude –3.9 and high at magnitude –2.0, respectively. The gap between them continues to widen by about 1° per day. They will be about 32° apart on Saturday. Both are about at their farthest from Earth. Gemini heads, Castor and Pollux, sit to the left of Jupiter.
Mars, at magnitude 1.6 in the constellation of Virgo, sits very low in the west as twilight fades. Use binoculars to try to catch it about 40 minutes after sunset a little above the west-southwest horizon. Twinkle star Spica will appear closest to Mars on Friday. They will be 2¼° apart.
Saturn, at magnitude +0.7 in the constellation of Pisces, looms low in the east-southeast. Saturn is nearing opposition and rises during bright twilight. The lower-left side of the Great Square of Pegasus points down nearly to Saturn. The Square is standing on one corner. Observe Saturn with a telescope after midnight when it’s highest toward the south.
Uranus, at magnitude 5.7 in the constellation of Taurus near the Pleiades, rises around 10pm. It gets high in the east in the early morning hours.
Neptune, at magnitude 7.8, sits less than 2° north of Saturn. Use the finder chart to help you locate Neptune with respect to Saturn.
Cassiopeia looks like the letter W or M. Cassiopeia in Greek mythology was Queen of Aethiopia (Ethiopia) and wife of King Cepheus. Look for the Queen starting at nightfall this month. She’ll be higher up in the northeast as autumn unfolds. Cassiopeia is a circumpolar constellation. It’s visible year-round in the Northern hemisphere,
spinning around the North Star without rising or setting. The W pattern of Cassiopeia stands on end in the northeast as evening proceeds. Find the W’s third segment counting from the top, follow the direction it points down by a little farther than the segment’s length. If you have a dark sky, look for an enhanced, irregular little spot of the Milky Way’s glow. Binoculars will show this to be the Perseus Double Cluster, NGC 869 and NGC 884