Skywatch Line for Friday, May 12, through Sunday, May 14, 2017

This is Dudley Observatory’s Skywatch Line for Friday, May 12, through Sunday, May 14, written by Sam Salem.

On Friday, Sun rises at 5:36am and sets at 8:09pm; the Waxing Gibbous Moon rises at 9:44pm, reaches transit altitude at 1:57am, and sets at 7:00am.

Venus, at magnitude –4.7, rises due east at 3:52am, on Saturday morning. The “morning star” is bright enough to be seen even after the Sun rises if you know where to look. Jupiter is up before sunset, shining at magnitude -2.4, and reaches the meridian around 10:27pm, on Friday. About 15 minutes later, Saturn, at 0.2 magnitude, climbs to southeast horizon. The ringed planet is at its highest altitude of 25 degrees south around 3:21am, as morning twilight begins to brighten the sky. The waning gibbous Moon makes a triangle with Saturn and the star Antares. Watch for this celestial triangle to illuminate southeast sky by mid-to-late evening. On Saturday evening, the Moon will be positioned roughly 3½ degrees to the left of Saturn as the pair rises together in the southeast. Saturn now shines in front of the constellation Sagittarius, but will cross over into the constellation Ophiuchus after a few more days. Saturn will be considerably closer to Antares on the sky’s dome at the end of its retrograde on August 25.

NASA scientists have called the space between Saturn’s rings “the big empty,” after interpreting readings from the Cassini spacecraft. During the first of its final dives, Cassini revealed the void between the rings is largely dust-free. If the environment were very dusty, scientists would hear dust hitting the spacecraft as a lot of crackling and popping in the readings. However, as Cassini entered the 1,200-mile-wide void, scientists heard very little. Cassini ventured into the space between Saturn’s rings on April 26.

Regulus, in Leo, the Lion, can be split in a small telescope even at low magnification. Its 8.2-magnitude companion lies 176 arc-seconds northwest of the 1.4-magnitude main star. Regulus sets at 2:32am on Saturday morning. Swing your telescope around and aim due north at Polaris, the Pole star. Alpha Ursae Minoris is also a striking double featuring components that span a range of brightness similar to the Regulus twosome. A 9.1 magnitude companion, 18.6 arc-seconds away, accompanies the 2.1 magnitude Pole star.

As evening falls in the month of May, the plane of the pancake-shaped galactic disk of our Milky Way coincides with the plane of the horizon. The Milky Way rims the horizon in every direction at nightfall and early evening, which makes it difficult to see this roadway of stars until later at night. By June, you’ll begin to see the stars of the Summer Triangle, Deneb, Vega, and Altair rising above eastern horizon earlier at night. In a dark country sky, the Milky Way’s band of stars becomes visible as well, for the Milky Way passes right through the Summer Triangle. The Milky Way’s softly glowing band of luminescence hides behind the horizon at nightfall and early evening in the month of May. You’ll begin to see the starlit band of the Milky Way rising in the eastern sky around midnight.

On May 14, 1973, the United States launched its first manned space station “Skylab One”. During the following nine months, three successive crews of astronauts manned the orbiting laboratory. This was the largest payload launched into space. It fell back into and burned up in the Earth’s atmosphere in July 1979.

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