Skywatch

By CHRIS PAGAN

Sunday: The last quarter moon takes place at 4:20 p.m. today. The moon will not rise until 12:14 a.m., making it a good night to find a nice pair of open star clusters. In the constellation of Perseus there is a pair of open star clusters very near each other. The two clusters are found halfway between the head of the constellation Perseus and the constellation Cassiopeia in the north-northeast. The two clusters are about 12 degrees above the horizon at 10 p.m. Without using a telescope or binoculars, this pair of open clusters looks like a hazy patch of light under dark skies. With binoculars, dozens of stars will resolve themselves into points of light.

Monday: Tonight after sunset, Jupiter dominates the sky as the brightest object visible. In a small telescope, four of the planet’s moons will be visible with three of them on one side of Jupiter. The planet is located 5 degrees directly above the red supergiant star Antares.

Tuesday: When the crescent moon rises in the early morning hours, it will be 3-1/2 degrees from the Pleiades star cluster. Mars is also in the same region of the sky, 5 degrees below the Pleiades and 6-1/2 degrees to the lower right of the moon.

Wednesday: At 10 p.m. the constellation of Lyra the Harp is nearly directly overhead and resembles a diamond. The brightest star in the constellation is Vega, and is easily the brightest star in this region of the sky. Opposite of Vega in the diamond are the stars Sulafat and Sheliak both similar in brightness. Halfway between these two stars lies one of the most popular planetary nebulae, the Ring Nebula. The Ring Nebula appears as a faint small halo through a telescope.

Thursday: Looking toward the star Sheliak in Lyra, it can be observed to change in apparent brightness. Sheliak is a double star in which the stars eclipse one another as seen from Earth. Sheliak’s brightness can vary from being as bright as Sulafat to as dim as Zeta Lyrae. Zeta Lyrae is located 2 degrees below Vega. The change in brightness occurs regularly every 12 days and 22 hours.

Friday: At 6 a.m., a thin crescent moon will be visible in the eastern sky. The moon is currently in the middle of the constellation of Gemini, the twins.

Saturday: In the predawn sky today, Mars lies halfway between the two star clusters Pleiades and Hyades in the eastern sky. One hundred and twenty years ago when Asaph Hall, an American astronomer, observed Mars on this date he discovered Mars’ small moon, Deimos. Six days later he would discover the larger moon, Phobos. These moons are visible through a telescope, but are extremely difficult to see because Mars appears more than 200,000 times brighter than the moons. Several modifications need to be made to an eyepiece to have a chance of finding either moon.

Chris Pagan is planetarium director at Tulsa Air and Space Museum, www.tulsaairandspacemuseum.com