Skywatch Line for Friday, April 24, through Sunday, April 26, written by Sam Salem
This is Dudley Observatory’s Skywatch Line for Friday, April 24, through Sunday, April 26, written by Sam Salem.
On Friday, Sun rises at 6:00am and sets at 7:48pm; Moon sets at 2:47am and rises at 12:29pm.
On Friday evening, turn your telescope toward the Moon to scan around the sunlit portion of the disk as the terminator dividing night and day continues sweeping westward. The dark and circular Sea of Serenity appears just northeast of the terminator in the Moon’s northern hemisphere. Look along the northeastern rim of this mare to find the well-defined crater Posidonius. Use a map to help you locate the Moon features.
On Friday and Saturday evenings, the waxing gibbous Moon will be near 1st-magnitude Regulus, the brightest star in Leo the Lion. Regulus is the bright star at the bottom of a backward question-mark pattern of stars, also known as the Sickle. They’ll set several hours after midnight. On Saturday, Regulus is 0.2 degrees south of the Moon. Regulus will vanish behind the Moon’s dark limb during twilight for the much of the Eastern North American Seaboard.
On Friday, Venus passes 0.8 degrees due north of Uranus at 1 am.
Uranus, magnitude 5.8 in constellation of Taurus, is a faint object passing in the background of Venus. They were in conjunction on Thursday. They’ll be very low by the time the sky becomes dark enough.
Venus, at magnitude –3.9, glows low in the west-northwest in evening twilight. An hour after sunset you’ll find it about a fist at arm’s length above horizon. Venus sets a half hour after twilight ends. Venus passed the Pleiades this week. It was in conjunction with the Pleiades on Thursday.
Jupiter, magnitude –2.0, shines high toward the west at nightfall, about 50 degrees to Venus’s upper left. Jupiter moves lower through the evening and sets around 2 am on the west-northwest horizon. In a telescope Jupiter is down to 37 arcseconds wide. It’s shrinking and fading as Earth pulls farther ahead of it in our faster orbit around the Sun.
On Friday, watch Jupiter approaching little Delta Geminorum, or “Wasat”, in the middle of constellation Gemini. They’ll be down to 1.0° apart.
Mercury, Mars, Saturn, and Neptune are very low in the brightening glow of sunrise. Using binoculars or a telescope at low power, you might try for them just a few degrees above the horizon almost due east, about 20 minutes before sunrise. Best chance will be to catch Mercury, the brightest of them, at about magnitude –0.3.
The waxing Moon is in eastern part of constellation Cancer on Friday evening, not far from the Beehive open cluster (M44). This star cluster is a great binocular target even with the Moon nearby. M44 shines at third magnitude and covers roughly a degree on the sky.
Pollux and Castor, the heads of the Gemini twins, form the top of the enormous “Arch of Spring” asterism. look up in the west for Pollux and Castor lined up almost horizontally as night descends. To their lower left is Procyon, the brightest star in constellation Canis Minor, the left end of the Arch. Farther to their lower right is the other end, formed by 2nd-magnitude Menkalinan, Beta Aurigae, and then brilliant Capella, in the constellation of Aurigae. The whole asterism sinks in the west through the evening.
Extend the asterism down past Procyon to add Sirius, to have the shape of a bailer, the “Hawai‘ian Canoe-Bailer of Makali‘i”.