Skywatch Line for Friday, May 1, through Sunday, May 3, written by Sam Salem

This is Dudley Observatory’s Skywatch Line for Friday, May 1, through Sunday, May 3, written by Sam Salem.

On Friday, Sun rises at 5:49am and sets at 7:56pm; Moon sets at 5:21am and rises at 8:22pm.

Full Moon occurs at 1:23 pm, on Friday. The full Flower Moon will lie between Antares, brightest star in Scorpius, and Spica, brightest star in Virgo. Also, the Moon will be close to the star Zubenelgenubi, brightest star in Libra. This is the first Full Moon of two that occur in the month of May. The second Full Moon on May 31 will bring the year’s first and only Blue Moon.

Late on Saturday evening, the waning gibbous Moon will be near Antares. They’ll be visible until dawn.

Venus shines on the western side of the sky in twilight above Aldebaran and Pleiades. Venus, at magnitude –3.9, shines low in the west-northwest in evening twilight. It doesn’t set until about 40 minutes after twilight’s end.

Saturn and Mars continue to pull farther apart, low in brightening dawn. On Saturday morning, they’re separated by 8°. A week later they’ll be 13° apart. The change is almost entirely due to Saturn moving up and right with respect to dawn horizon. Mars appears to stay at nearly a fixed height.

Saturn, at magnitude 0.9, rises early in the morning, a bit easier to spot in the predawn sky about 45 minutes before sunrise when it has reached an altitude of nearly 4° above the eastern horizon. Saturn is in constellation of Cetus, the Whale or Sea Monster. Look for Saturn hanging below the Great Square of Pegasus.

Mars lies 7.6° east of Saturn, to its lower left. Mars is much lower, just under 2° high, and at magnitude 1.2. This makes it a bit harder to spot. Try to catch it with binoculars or a small scope.

Jupiter, magnitude –2.0, shines high toward the west at nightfall about 40° to Venus’ upper left. Jupiter sinks through the evening and sets around 1 am on the west-northwest horizon. Watch Jupiter and Venus close in toward each other for the next few weeks. They’ll pass 1.6° apart at their conjunction on June 9th.

Watch Jupiter passing little Delta Geminorum (Wasat) in the constellation Gemini the Twin. Delta Gem, magnitude 3.5, is the waist of the Pollux stick figure. They pass closest, 0.6° apart, on Thursday-Friday night. Jupiter won’t pass Delta Gem again until 2037. In a telescope Jupiter is down to 36 arcseconds wide. It continues to shrink and fade as Earth pulls farther ahead of it in our faster orbit around the Sun.

The Great Diamond is a gigantic asterism, some 50° tall and extending over five constellations. It now leans left in the southeast after dusk, over the Moon on Saturday night. Start with Spica, in the bottom. Move upper left from Spica to bright Arcturus. Almost as far upper right from Arcturus is fainter, 3rd magnitude, Cor Caroli. A similar distance lower right from there is the 2nd-magnitude Denebola, the tail tip of Leo. Then back to Spica. The brightest bottom three of these stars form an equilateral triangle. They are occasionally referred to as the “Spring Triangle.”