Skywatch Line for Friday, September 15, through Sunday, September 17, 2023

This is Dudley Observatory’s Skywatch Line for Friday, September 15, through Sunday, September 17, written by Sam Salem.

On Friday, Sun rises at 6:35am and sets at 7:05pm; Moon rises at 6:57am and sets at 7:32pm.

Watch for Venus in the east before sunrise. Look in the sunset direction on any clear morning around now. Venus will reach its greatest illuminated extent in our morning sky on Tuesday. It won’t reach brightest brilliancy again until February 2025 when it’s in the evening sky. When it’s this bright, Venus appears as an eye-catching beacon in the morning sky. It’s visible in bright morning twilight as well. Venus is rapidly getting higher in the east before and during dawn. By the end of this week, it comes up over the east horizon nearly two hours before dawn’s first light.

Jupiter, at magnitude –2.6 in the constellation of Aries, rises in the east-northeast not long after dark. It shines highest in the hours before dawn.

Saturn, at magnitude +0.5 in dim constellation of Aquarius, sits low in the southeast in twilight. It’s two weeks past opposition. It shines at a good height for telescopic observing by 10pm. Saturn is highest in the south around midnight.

Uranus, magnitude 5.7 in Aries, is nice and high in the hours before dawn, 7° or 8° east of Jupiter.

Neptune, at magnitude 7.8 at the Aquarius-Pisces border, is high in the southeast by 10 pm. It sits 24 degrees east of Saturn. Neptune will be in opposition on Tuesday.

That 1st-magnitude star high in the south after dark is Altair. Look for its little marker Tarazed, 3rd magnitude, about a finger-width at arm’s length to Altair’s upper right.

About a fist to Altair’s upper left is the little constellation Delphinus, the Dolphin. Not quite as far straight above Altair is smaller, fainter constellation Sagitta, the Arrow.

Look very low in the west-southwest during twilight for the waxing crescent Moon. As twilight deepens, see Spica twinkling 4 degrees lower right of it. Next, look due west about 25 degrees to the right of the Moon, far below Arcturus, for Comet Nishimura at perihelion. Use binoculars. You have a narrow time window between when twilight is still too bright and the comet gets too low and sets.

use Polaris and the Little Dipper to find the constellation Cepheus the King. It lies adjacent to Polaris, the North Star. It’s also near the northern asterism of the Little Dipper, in the constellation Ursa Minor. Look for a five-sided pattern of stars that resembles a child’s drawing of a house. Sometimes this stick house is right side up. And at other times it appears to stand on its side or roof. Cepheus may be found by drawing a triangle between the familiar Little Dipper asterism, the W-shaped constellation Cassiopeia, and the cross-shaped constellation Cygnus the Swan. Inside that triangle, you’ll find a pentagon of stars. This pentagon is Cepheus. Named for an ancient king of Ethiopia, Cepheus figures in one of the most intricate legends of the night sky. His

legend involves many nearby constellations. Cassiopeia the Queen represents the wife of Cepheus. She’s seen as seated beside him in the sky. The constellation Andromeda the Princess or Chained Lady resides in the sky on the other side of Cassiopeia.

According to the myths, Andromeda’s parents chained her up and presented her as a sacrifice to the sea god Poseidon. But as the sea monster Cetus was on its way to devour Andromeda, Perseus the Hero rode in on Pegasus the Winged Horse. Perseus saved Andromeda from the sea monster.