Skywatch Line for Friday, June 23, through Sunday, June 25, 2023
This is Dudley Observatory’s Skywatch Line for Friday, June 23, through Sunday, June 25, written by Sam Salem.
On Friday, Sun rises at 5:17am and sets at 8:38pm; Moon rises at 10:14am. First-quarter Moon occurs at 3:50am Monday morning.
The waxing crescent Moon will glow near the planets Venus and Mars, plus the bright star Regulus, in the constellation of Leo the Lion, on Friday evening. It will also lie near the dim star asterism, known as the Sickle. Catch the Moon and the Sickle until around midnight.
On Sunday evening, the Moon will lie along the southern edge of the star pattern known as the Spring Triangle. The Spring Triangle is an asterism made of the bright starts Arcturus, in the constellation of Boötes the Herdsman, Spica, in the constellation of Virgo the Maiden, and Denebola, in the constellation of Leo the Lion at its corners. The Moon and the Spring Triangle will be visible through about an hour after midnight. Sometimes the Spring Triangle is listed with Regulus instead of Denebola as the 3rd star.
Venus, at magnitude –4.6 in Cancer, is the brilliant “Evening Star” in the west through twilight into dark. It’s getting lower every week. It now sets less than an hour after full darkness.
Mars, at magnitude 1.7, crossing from Cancer into Leo, glows weakly a little to Venus’s upper left, by a slightly shrinking distance of 4.1° on Friday. Mars and Venus will reach a minimum separation of 3.6° next Friday. Then they’ll start to draw apart again as Venus plunges down toward the sunset.
Jupiter, at magnitude –2.2 in Aries, is that bright “star” in the east before and during early dawn.
Saturn, at magnitude +0.9 in dim Aquarius, rises around 1am. By the beginning of dawn, Saturn sits in a good telescopic view high in the southeast.
This is the time of year when the two brightest stars of summer, Arcturus, and Vega, are about equally high overhead shortly after dark. Arcturus sits toward the southwest, Vega sits toward the east. Arcturus and Vega are 37 and 25 light-years away, respectively. Arcturus is a yellow-orange K giant, and Vega is a white A main-sequence star. They’re 150 and 50 times brighter than the Sun, respectively.
On Summer nights, a famous pair of stars peers down at us from the northern sky. The two stars are Eltanin and Rastaban. They represent the fiery eyes of the constellation of Draco the Dragon. Eltanin and Rastaban are very noticeable. They’re like the two stars of the constellation of Gemini the Twins, Castor, and Pollux. And they’re like the Little Dipper’s bowl stars Kochab and Pherkad. Each of these starry pairs is easy to spot.
Once you become familiar with the brilliant Summer Triangle star pattern, it’s easy to star-hop to the Dragon’s eyes. Draw an imaginary line from the star Altair through the star Vega to locate nearby Eltanin and Rastaban. The Dragon’s eyes appear in the
northeast sky on Spring evenings, nearly overhead on late summer evenings, and in the northwest evening sky in late Autumn and early Winter.