Skywatch Line for Friday, May 3, through Sunday, May 5, written by Sam Salem
This is Dudley Observatory’s Skywatch Line for Friday, May 3, through Sunday, May 5, written by Sam Salem.
On Friday, Sun rises at 5:46am and sets at 7:59pm; Moon rises at 3:36am and sets at 2:39pm.
At the beginning of morning twilight, on Friday, the waning crescent Moon will float near Saturn, Mars, and Mercury. The lit portion of the Moon will point toward Saturn.
On Saturday before dawn, the waning crescent Moon will float between Saturn and Mars. Mercury will lie near the horizon. The lit portion of the Moon will point toward Mars.
On Sunday before sunrise, the waning crescent Moon will lie near Mars. And they’ll be between Saturn and Mercury.
The Moon will reach perigee, its closest point in its elliptical orbit around Earth, on Sunday, when it’s 225,659 miles away.
The Eta Aquariid meteor shower, bits of the rubble stream shed by Halley’s Comet, often presents the best meteor display of the year for the Southern Hemisphere. But for us northerners the shower’s radiant point is still quite low even as dawn begins. The best time to watch the Eta Aquariid meteor shower will be before dawn on Sunday and Monday. With the new Moon a few days away, there won’t be any moonlight to hinder meteor watching. Under ideal conditions, you might see around 20 meteors per hour. The meteor shower radiant will rise in the wee hours, climbing toward its highest point at dawn.
On Friday after sunset, use binoculars or a wide-field telescope to try for a last look at Jupiter. It’s just above the west-northwest horizon in moderately bright twilight. This could be the last chance to see the giant planet so close to the end of its 2023-24 apparition.
The spring sky offers the best views of the asterisms in the constellation Ursa Major, Boötes, Leo, Virgo, Centaurus, and Crux. The stars of some of these constellations form two large seasonal asterisms: the Spring Triangle and the Diamond of Virgo, or the Great Diamond. The gigantic spring asterism, the Great Diamond, is about 50° tall and extending over five constellations. The Great Diamond now stands upright in the southeast to south after dusk. Start with Spica, its bottom. Upper left from Spica is bright Arcturus. Almost as far upper right from Arcturus is fainter Cor Caroli, 3rd magnitude. The same distance lower right from there is Denebola, the 2nd-magnitude tail tip of Leo.
The bottom three of the Great Diamond stars, the brightest, form a nearly perfect equilateral triangle. It’s called the “Spring Triangle” to parallel to those of summer and winter. Spring Triangle isformed by Arcturus, Spica and Regulus, the brightest stars in the constellations of Boötes, Virgo and Leo. The Spring Triangle is easily found using the stars of the Big Dipper. Arcturus and Spica are the brightest stars on the imaginary curved line extended away from the Dipper’s handle, and Regulus lies on the line drawn from the inner stars of the Dipper’s bowl, Megrez and Phecda. Each of the three stars of the Spring Triangle lies at the base of its own constellation-based asterism: Arcturus in the Kite, Spica in the Y of Virgo, and Regulus in the Sickle.
If you have a dark sky, or binoculars, look halfway from Cor Caroli to Denebola for the very large, sparse Coma Berenices star cluster. It is the haze on the Diamond’s edge. It spans some 4°, about the size of a ping-pong ball held at arm’s length.