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This is the Griffith Observatory Sky Report through December 23, 2015. Here’s what’s happening in the skies of southern California.
The winter solstice occurs at 8:48 p.m., PST on Monday the 21st. It is the start of winter in the northern hemisphere and the start of summer in the southern hemisphere. From Griffith Observatory, the sun makes its lowest local noon appearance, located due south and 32½ degrees above the horizon at 11:51 a.m. The southernmost sunset of the year occurs at 4:48 p.m. The public is invited to attend two free Observatory events to mark the start of winter. Members of the Observatory staff will observe the solstice noon at the Gottlieb Transit Corridor, west of the building, beginning at 11:45 a.m. The solstice sunset will be observed from the western walkway’s inscribed seasonal lines, adjacent to the western side of the building, starting at 4:40 p.m. As is usual for a Monday, the rest of Griffith Observatory will not be open to the public. The winter season will end with the start of spring on March 19, 2016.
Between the 16th and 23rd, the phase of the moon changes from waxing crescent to waxing gibbous and is first quarter on Friday the 18th. The moon lights the sky for about an hour longer each night. The time of moonset advances from 10:24 p.m. on the 16th to 4:53 a.m. on the 23rd.
The brilliant planet Jupiter, in the constellation Leo the Lion, rises in the east at around midnight, then crosses the meridian 61 degrees high in the south at the start of dawn. Through a telescope, Jupiter’s disk shows bands of clouds. Binoculars, if steadily held, are just sufficient to show Jupiter’s four largest moons.
Orange planet Mars, in the constellation Virgo the Maiden, rises in the east-southeast about two hours after Jupiter. Mars appears about four degrees above Virgo’s brightest star, Spica. Spica’s blue-white hue contrasts with the rusty tone of Mars. At the start of dawn, Mars is 42 degrees high in the southeast.
The brightest planet Venus, rises by 3:48 a.m. in the east-southeast, and is 25 degrees high at dawn. At that time Jupiter is 55 degrees to the upper right of Venus. Mars is near the middle of the imaginary line between the two brighter planets.
The ringed planet Saturn can be seen briefly starting at about 6:05 a.m., before the dawn’s light becomes too bright. Binoculars will help you to find Saturn five degrees above the east-southeast horizon.
Comet Catalina, C/2013 US10, moves higher into the morning sky, roughly along a line between Venus and the bright orange star Arcturus of the constellation Boötes the Herdsman. The brightness of the comet is reported to be magnitude 6.3, and is visible in binoculars. Starting on December 24, bright moonlight will interfere with observations. A detailed finder chart can be found on the Sky and Telescope Comet Catalina webpage.
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 the schedule. 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 19.
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From Griffith Observatory, I’m Anthony Cook and I can be reached at griffithobserver@gmail.com