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This is the Griffith Observatory Sky Report for the holiday period ending Wednesday, January 7, 2015. Here is what’s happening in the skies of southern California:
The winter solstice occurs at 3:03 p.m., PST, on the 21st. The moment is the start of winter in the earth’s northern hemisphere and the start of summer in the southern. It is also the moment when the sun appears to reach its southernmost point in the sky. The winter season will end with the vernal equinox on March 20, 2015.
The earth is at perihelion (closest to the sun) on January 4 at 6:36 a.m., PST. At that time the center of our planet will be 91,406,346 miles from the center of the sun, some 1,549,461 miles closer than the average and 3,105,158 miles closer than we shall be from the sun at aphelion (farthest from the sun) on July 6, according to the NASA/JPL Horizons on-line calculation system.
The moon will be new at 5:36 p.m. on the 21st, only 2½ hours after the solstice. It will be visible on the mornings before that in waning crescent phase until the 20th, and will appear in the evening sky on December 22. It becomes first quarter on the 28th, and is full on the night of January 4. One traditional name for the full moon of January is the Wolf Moon.
Nautical twilight is defined as starting when the sun is 6 degrees below the horizon. From the latitude of Los Angeles, 34 degrees north, nautical twilight starts about half an hour after sunset, and occurs at 5:15 p.m. in late December. Evening nautical twilight is when the bright planets first become visible, and is the best time to find the planets Venus and Mars, and starting on December 31, Mercury. Venus, the brightest planet, should be visible only 4 degrees above the southwest horizon on the 17th, and will steadily gain elevation night after night, until by January 6, it is 9 degrees high at the start of nautical twilight. On December 31, use binoculars to find Mercury 3 degrees (about a third of the binocular field of view) below Venus. Mercury will be only 1.2 degrees below Venus on January 6. Throughout this period, the orange planet Mars appears about 20 degrees above and to the left of Venus.
Brilliant cream-yellow Jupiter, in Leo the Lion, rises above the east-northeast horizon by 9:00 p.m. It is highest, shortly after midnight, and is still visible, high in the west at sunrise. Binoculars are sufficient to see Jupiter’s four Galilean satellites. A telescope, however, is needed to see the cloud details on Jupiter’s disk. The moons will also provide interesting views. On December 21st, the moon Europa will quickly fade to a third its normal brightness when it is eclipsed by the shadow of Jupiter’s largest moon, Ganymede between 3:48 and 4:12 a.m., PST. On December 30, the shadows of the moons Europa and Io will be visible as they cross Jupiter’s disk between 1:58 and 5:05 a.m., PST.
Just before dawn the golden planet Saturn, in Libra the Scales, can be found between 10 and 20 degrees above the southeast horizon. Saturn is directly above the orange star Antares of Scorpius the Scorpion. Antares and Saturn appear similar in brightness. A telescope is needed in order to see Saturn’s rings, now inclined 24 degrees in our direction. The waning crescent moon is 3 degrees above Saturn at dawn on Friday, December 19.
Comet Lovejoy (C/2014Q2) is quickly brightening as it moves into view from the southern hemisphere. The comet has been reported as just visible to the unaided eye, and is easy to see in binoculars from areas free of light-pollution. It could grow in brightness by a factor of six (from magnitude 6 to magnitude 4) by early January. Comet Lovejoy is best seen at about 1 a.m. Until December 25, the comet can be found about a third the way from the bright star Canopus to the brightest nighttime star, Sirius. The comet will travel northwestward from Columba the Dove to Lepus the Hare on December 28, and into Eridanus the River, about 10 degrees to the lower right of Orion the Hunter’s brightest star, Rigel, on January 2. Finder charts are available on the Sky and Telescope website.
The cargo supply mission (called CRS-5) to the International Space Station has been re-sheduled to Friday, December 19. As the first stage booster of the SpaceX Falcon 9 falls back to earth after performing its role in the launch, an attempt will be made to land it upright and gently on a special barge in the Atlantic Ocean. This is a test by SpaceX to lower launch costs by making re-usable rockets. The launch is scheduled to take place at 10:20 a.m., PST. Coverage should be provided on the NASA-TV and SpaceX websites.
Free views of the sun during the day and of the moon, planets, and other 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 our schedule. Because of the holidays, telescopes will not be open at night on December 24, 25, or December 31. The next 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, December 27.
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From Griffith Observatory, I’m Anthony Cook and I can be reached at griffithobserver@gmail.com.