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This is the Griffith Observatory Sky Report through January 10th, 2018. Here’s what’s happening in the skies of southern California.
The moon slips out of the evening sky as its orbit around the Earth causes it to rise about 30 minutes later, night after night. It rises at 7:11 p.m. on the 3rd and at 1:24 a.m. on the 10th. During this period, the moon’s waning phase is gibbous until it becomes last quarter on the 8th. Afterwards, it is crescent through the remaining nights.
The decrease in moonlight will improve conditions for becoming acquainted with the winter stars. To learn your way around the nighttime sky, it is useful to look for distinctive groupings of stars that form imaginary figures called constellations. The most recognizable winter constellation is Orion the Hunter. To find Orion, look to the east-southeast as soon as the sky grows dark. Just above the horizon, you should notice a compact, nearly straight line of three evenly spaced stars, forming the belt of the imaginary hunter, who is tilted over to the left as he rises above the eastern horizon. The other bright stars of Orion form a large rectangle enclosing the belt; the stars marking Orion’s shoulders, including the brilliant orange star Betelgeuse, are to the upper left of the belt. The stars forming his knees are closer to the horizon, to the lower right of the belt. The brilliant blue-white star on the lower right is named Rigel. A little harder to see, but appearing bright in binoculars, are three stars below the belt that form a line nearly perpendicular to it. This is called the Sword of Orion. Binoculars will reveal that the sword consists of many stars, and that its center contains a hazy glowing cloud. The Latin word for cloud is nebula, and this glowing patch is known as the Orion Nebula. It is a vast region of star formation in our Milky Way galaxy, and it is located about 1,400 light years away from us. It is one of the objects currently featured through the public telescopes at Griffith Observatory.
Several bright planets are visible at dawn. Brilliant Jupiter and orange Mars make an eye-catching pair of objects in the southeast sky. On the morning of the 3rd, Mars is 1½ degrees to the upper right of Jupiter, but by the 6th, the planets will be separated by only a quarter degree, close enough to fit into a single eyepiece field of view through a telescope. On the following morning, Jupiter moves to the upper right of Mars, and by the 8th, the planets are ¾ degree apart. To the lower left of the Jupiter-Mars pair is the bright orange star Antares in the constellation Scorpius the Scorpion, and it is located midway between the planets and the horizon. Antares means the “rival” or “equal” of Mars in Greek, and it refers to the similar orange hue shared by the star and the planet. Continuing the line made between the pair of planets and Antares toward the horizon will bring you the innermost planet, Mercury, and between Mercury and the horizon, is the golden planet Saturn. The moon will join this long line when it appears to the upper right of Jupiter and Mars on the 8th.
Free views of the Sun during the day and of other interesting celestial objects at night are available to the public in clear weather through Griffith Observatory’s telescopes from Tuesday through Sunday, before 9:30 p.m. Check our website for the schedule. The next free public star party on the grounds of Griffith Observatory, hosted by the Los Angeles Astronomical Society, the Sidewalk Astronomers, and the Planetary Society, will take place on Saturday, January 27th.
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From Griffith Observatory, I’m Anthony Cook, and I can be reached at griffithobserver@gmail.com.