Skywatch Line for Friday, August 23, through Sunday, August 25, written by Sam Salem
This is Dudley Observatory’s Skywatch Line for Friday, August 23, through Sunday, August 25, written by Sam Salem.
On Friday, Sun rises at 6:11am and sets at 7:44pm; Moon sets at 10:55am and rises at 9:45pm.
The brightest star high in the southeast these moonless evenings is Altair, with little orange Tarazed above it by a finger-width at arm’s length. A little more than a fist-width to Altair’s left is delicate constellation of Delphinus, the Dolphin. Above Altair, slightly less far, is smaller, fainter constellation of Sagitta, the Arrow. It is pointing leftward. You’ll need a nice dark sky to locate these dark constellations.
Milky Way time is when the Moon is out of the August evening sky. After dark now the Milky Way runs from Sagittarius in the south, up and left across Aquila and through the big Summer Triangle very high, and on down through Cassiopeia to Perseus low in the north-northeast.
On Saturday, the Moon, nearly last quarter, rises around 11 p.m. Once it’s well up an hour or two later, look for the Pleiades about a fist at arm’s length to its lower left.
Last-quarter Moon occurs at 5:26 a.m. Monday morning. The Moon is now a few degrees lower left of the Pleiades.
On Sunday, Algol in the constellation of Perseus shines two fists upper left of the Moon. Catch Algol doing one of its self-eclipses, changing magnitude to 3.4 instead of its usual 2.1, for a couple hours centered on 3:13 a.m. Monday morning. Algol takes several additional hours to fade and to re-brighten.
Venus, magnitude –3.8, is very low above the west horizon in bright twilight. It’s getting slightly more visible week by week. Look for it with binoculars a little to the right of due west starting 15 or 20 minutes after sunset.
Mars and Jupiter, magnitudes +0.8 and –2.3, respectively, in the constellation of Taurus, are pulling apart from each other in the early-morning sky. Watch for them to rise in the east-northeast around 1 a.m. Jupiter is up first. Mars, much fainter, follows closely at its lower left. But less closely every night. Last Saturday morning the two planets were just 1° apart. This Friday, they’ve widened to 4.4° apart.
By the first sign of dawn, Jupiter and Mars are high up in the east. Aldebaran shines to their right, and the horn-tip stars of the constellation of Taurus sit to their left and lower left. Orion is down below.
Saturn, magnitude +0.7, south of the Circlet of the constellation of Pisces, glows low in the east as evening twilight fades away. It’s lower right of the Great Square of Pegasus, which is balancing on one corner. Saturn shines highest toward the south in the hours after midnight, through less of blurry atmosphere for better telescopic viewing.