This is Dudley Observatory’s Skywatch Line for Friday, May 26, through Sunday, May 28, written by Sam Salem.
On Friday, Sun rises at 5:23am and sets at 8:22pm; Moon sets at 1:32am and rises at 11:23am. The Moon, very nearly first quarter, shines in the Sickle of Leo after dusk on Friday. It’s almost between the Sickle’s two brightest stars, Regulus, lower left of the Moon, and fainter Gamma Leonis or Algieba, to the Moon’s upper right.
First-quarter Moon occurs on Saturday at 11:22 a.m. That evening, the Moon shines under Leo’s midsection, not quite halfway from Regulus lower right of the Moon to Beta Leonis or Denebola, the Lion’s tail-tip, to the Moon’s upper left.
Venus, magnitude –4.3, in the constellation of Gemini, is the brilliant “Evening Star” in the west from twilight into late evening. It still shines nearly as high in the dusk as it ever gets, and it doesn’t set until about 2 hours after dark. Venus is enlarging a little more every day while waning in phase. Next week it’ll appear half lit, then it will become a bigger, dramatically thinning crescent dropping low from mid-June through mid-July.
Mars, magnitude 1.6, in the constellation of Cancer, glows weakly to the upper left of Venus by an ever-shrinking distance of 12° by Sunday. That’s hardly more than a fist at arm’s length. They will not reach conjunction. Mars and Venus will reach a minimum separation of 3.6° on June 30th, then they’ll start to draw apart again as Venus plunges down toward the sunset. This is called a quasi-conjunction, because they don’t pass each other although they do get within 5° of each other.
Jupiter, magnitude –2.1, in the constellation of Aries, is beginning to emerge from the bright glow of sunrise. Look for it very low in the east in about 40 minutes before sunup.
Saturn, magnitude +1.0, in the dim constellation of Aquarius, is moderately low in the southeast before and during early dawn.
Bright star Capella, in the constellation of Auriga the Charioteer, sets low in the northwest soon after dark. That leaves Vega and Arcturus as the brightest stars in the evening sky. Vega, in the constellation of Lyra, shines in the east-northeast. Arcturus, in the constellation of Boötes, is way up very high toward the south. A third of the way from Arcturus to Vega, look for semicircular Corona Borealis, the Northern Crown, with 2nd-magnitude Alphecca as its one moderately bright star. It’s the jewel on the front of the tiara. Two thirds of the way from Arcturus to Vega is the dim Keystone of Hercules, now lying almost level. Use binoculars or a telescope to examine the Keystone’s top edge. A third of the way from its left end to the right is 6th-magnitude M13, one of Hercules’s two great globular star clusters. In binoculars it’s a tiny glowing cotton ball.