Skywatch Line for Friday, May 16, through Sunday, May 18, written by Sam Salem
This is Dudley Observatory’s Skywatch Line for Friday, May 16, through Sunday, May 18, written by Sam Salem.
On Friday, Sun rises at 5:31am and sets at 8:13pm; Moon sets at 7:55am.
In the early morning hours of Friday, the waning gibbous Moon will float among the stars of the Teapot asterism of Sagittarius the Archer. It will be near the direction of the center of the Milky Way galaxy.
The brightest asteroid, 4 Vesta, is two weeks past opposition. It’s nicely placed this weekend in a moonless dark sky in late evening. The asteroid is magnitude 5.9, about 24° below Arcturus, near the Virgo-Libra border above Beta and Alpha Librae. Vesta is now an easy catch in binoculars. Also, if you have a dark sky, you might be able to detect it now with the unaided eye. It’s the only naked-eye dwarf planet and its a few days past its opposition. You’ll need a finder chart.
Venus and Saturn rise nearly two hours before sunrise. Venus, magnitude –4.7, shines 230 times brighter than Saturn. Venus is a thick crescent, about 37% sunlit. Use binoculars to help you locate Saturn, 12° to the upper right of Venus on Saturday.
Both will be blurred in a telescope in the low altitude seeing. Saturn’s rings are now turned nearly edge-on to Earth this year. In a telescope, they look like traces of a hair needle stuck diagonally through Saturn’s disk.
Mars, magnitude +1.1 in the constellation of Cancer, glows high in the southwest in the evening. It’s the orange dot about 2 fist-widths upper left of the Gemini Twin, Pollux and Castor. Mars and Pollux are the same brightness. Mars is more strongly tinted than pale yellow-orange Pollux. Farther below Mars shines Procyon, the brightest star in the constellation of Canis Minor. The Greek name “Procyon” translates to “foredog”. It refers to the rise of Procyon before Sirius, the Dog Star in the constellation of Canis Major. In a telescope, Mars looks as a fuzzy blob, only 6 arcseconds in diameter.
Jupiter, magnitude –2.0 in the constellation of Taurus, shines low in the west during and shortly after dusk and setting less than an hour after the end of twilight. It sits between Taurus’s two horn-tip stars, Beta Tauri to its upper right and fainter Zeta Tauri closer to its lower left. The three looked as a perfect straight line last night, May 15th. Jupiter has shrunk to only 33 arcseconds wide. It will be badly blurred by the low altitude seeing.
Vega, the summer star, is the brightest star in the east-northeast after dark. Look about a fist and a half at arm’s length upper left of Vega for Eltanin, the 2nd-magnitude nose of Draco the Dragon. Draco always points his nose to Vega, no matter how he’s oriented.
The two stars representing the fiery eyes of Draco are Eltanin and Rastaban. Eltanin means “the dragon” and Rastaban means “the serpent’s head” in Arabic. Closer above and upper left of Eltanin are the three fainter stars that form the rest of Draco’s stick-figure head, also called the Lozenge.