This is Dudley Observatory’s Skywatch Line for Friday, May 31 through Sunday, June 2, written by Sam Salem.
On Friday, Sun rises at 5:21am and sets at 8:27pm; the waning crescent Moon rises at 4:00am and sets at 5:29pm. On Saturday morning, the very thin waning crescent Moon and Venus have a low-lying conjunction at dawn. The Moon sits a little more than six degrees to the right of Venus. The objects are less than 10 degrees up by sunrise. You need an unobstructed east-northeast horizon and binoculars to view the conjunction. The new Moon occurs on Monday at 6:02am.
Mars sets around 11:45pm and Jupiter rises a few minutes after 9pm. By 10pm, Mars and Jupiter are both hovering only a few degrees above the horizon. Face west-northwest to spot Mars, glowing at magnitude 1.8 in constellation Gemini. Turn around to face the opposite direction and you’ll find Jupiter gleaming at magnitude –2.6 in the southeast. The two planets are opposite in the sky and they’re at opposite stages in their respective apparitions. Mars is slipping away, while Jupiter is nearing opposition. Jupiter climbs to its highest point around 1:30am, when it’s due south and ideally placed for telescopic inspection. Saturn rises in the east-southeast horizon a little after 11pm. Saturn, at magnitude 0.3, sits in eastern Sagittarius, and culminates shortly after 3:30am. Venus, at magnitude –3.8, rises less than an hour ahead of the Sun.
The dwarf planet Ceres reached opposition this week, which means it’s visible most of the night. At opposition, Ceres is closest to Earth and at peak brightness. Use this moonless weekend to observe the dwarf planet. Ceres appears as a 6.9-magnitude point of light in northern Scorpius, close to the border with Ophiuchus. The dwarf planet is near the meridian around 12:30am. The best way to locate your target is to use binoculars or a telescope at low power to scan west-northwest of 4th-magnitude Chi (χ) Ophiuchi. Use the method Giuseppe Piazzi used to be sure you have spotted Ceres, and not just a field star. Note your suspect’s position over a period of two or three nights. If it moves relative to the background stars. Then, you’ve found Ceres. When Giuseppe Piazzi discovered Ceres in 1801, he believed he had found a comet. Later, Ceres was thought to be the long-searched-for planet expected to circle the Sun between the orbits of Mars and Jupiter. When similar objects started turning up in the same zone, astronomers realized they had stumbled across a whole new class of solar system object. These bodies were called “minor planets” or “asteroids”. In 2006, Ceres was reclassified as a “dwarf planet”.
If you have a dark sky, you’ll be able to pick the constellation Draco, the Dragon, winding around the North Star, Polaris. The entire Dragon requires a dark sky to be seen. You’ll find the Big Dipper high in the north on June evenings. The two outer stars in the Dipper’s bowl point to Polaris, which marks the end of the Little Dipper’s handle. The Dragon winds between the Big and Little Dippers. A noteworthy star, Thuban, in constellation Draco is easy to find by looking between the Dippers. Although it’s not a super bright star, it is bright enough to see with relative ease on a dark night. Star-hop to Thuban from the Big and Little Dippers. Draw an imaginary line that connects the stars Pherkad, in the Little Dipper, and Mizar, in the Big Dipper. You’ll see Thuban midway between these two guide stars. Thuban is famous for having served as a pole star around 3000 B.C. There are two more prominent stars to look for in the Dragon. These stars are Eltanin and Rastaban. They lie in the head of Draco. They represent the Dragon’s Eyes. They’re noticeable because they’re relatively bright and near each other. The Dragon’s Eyes are near the blue-white star Vega. In Arabic, “Thuban” means “a snake”, “Eltanain” means “a dragon”, and “Rastaban” means “snake’s head”.