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This is the Griffith Observatory Sky Report for the week ending Wednesday, March 21, 2012 . Here is what’s happening in the skies of Southern California:
Following their conjunction on the 13th, the early evening show of the brightest planets, Venus and Jupiter, continues. Venus, the brightest of the pair, appears higher than Jupiter as the rapid orbital motion of Venus makes it swing out from behind the sun from our point of view. Jupiter, moving slowly around the sun, appears on successive evenings to approach the sun due to earth’s more rapid motion, which leaves Jupiter behind and beyond the sun. The apparent separation between Venus and Jupiter increases from 3 degrees to 7½ degrees between the 14th and 21st.
You can attempt to spot Venus in broad daylight when it crosses the meridian. Look 68 degrees above the south point on the horizon, more than 2/3 from the way from the horizon to directly overhead, at 3:50 p.m. each afternoon this week. Binoculars, focused first on a distant object, can make Venus much easier to see against the blue sky. A telescope will show the planet’s phase, slightly more than half lit this week.
Orange planet Mars, in Leo the Lion, continues to be visible through most of the night. It starts the evening high in the east, and is highest in the southern sky at 11 p.m. A telescope and steady air are needed to see the bright polar cap and dark regions of the planet.
The ringed planet Saturn, in Virgo the Maiden, shows up to the left of Virgo’s brightest star, Spica, low in the southeast by 10:00 p.m. Saturn crosses the Meridian 25 minutes after Spica, at about 3:00 a.m.
The waning moon is at last quarter phase on Wednesday night, March 14. Its rising time this week advances from 1:23 a.m. on the 14th to 5:08 a.m. on the 21st, when it appears just over a day from new as a slender crescent in the east.
The absence of bright moonlight will make this a weekend where some amateur astronomers will travel out to the wilderness with their club members to enjoy the sky without the hindrance of urban light pollution. This will be a great weekend to catch circumpolar comet Garradd, which moves from Draco the Dragon to northwestern Ursa Major on the 17th. Visible in binoculars or small telescopes at about magnitude 7, the comet will pass 5 degrees to the southeast of the bright galaxies M81 and M82 on Wednesday morning the 21st. Finder charts for comet Garradd can be generated on the satellite tracking website site www.heavensabove.com.
Early-risers in southern California will have their best view of the International Space Station, the brightest satellite, on Sunday morning, March 18. From Los Angeles, the ISS will cross the sky from southwest to northeast. It will emerge from earth’s shadow while 39 degrees high at 5:45 a.m., P.D.T., and will appear 80 degrees high in the northwest a minute later. It remains visible for another 4 minutes as it heads toward the northeast horizon. Passages of other satellites from any location can be found on www.heavens-above.com. The ISS is expected to appear at magnitude -3.5, a little dimmer than Venus.
Spring begins in the earth’s northern hemisphere at 10:14 p.m., P.D.T. on Monday, March 19.
Free public viewing of the sun during the day and of the moon, planets, and other celestial objects at night, is available in clear weather five days a week (Wednesday-Sunday) through Griffith Observatory’s telescopes before 9:30 p.m. Check our website for our schedule. The next public star party of the Los Angeles Astronomical Society and the Sidewalk Astronomers is scheduled for Saturday, March 31.
The Sky Report is updated every Wednesday. It can be read and heard on our website by following the Sky Information links. From Griffith Observatory, I’m Anthony Cook, and I can be reached at griffithobserver@gmail.com.