This is the Griffith Observatory Sky Report for the week ending Wednesday, September 12, 2012. Here is what’s happening in the skies of Southern California:

The ringed planet, Saturn, is challenging to see, low in the west-southwest during evening twilight and it sets at 9:30 p.m. Saturn is 5 degrees (half the distance covered by your clenched fist held at arm’s length) above Virgo the Maiden’s bright star, Spica.

Fifteen degrees to the upper left of Saturn is planet Mars, similar in brightness to Saturn and Spica. Mars is now in Libra the Scales. Because Mars orbits the sun much faster than Saturn, its motion will keep it visible low in the southwest for a few more months.

The waning moon rises an average of 43 minutes later each successive night this week, between 10:02 p.m. on the 5th to 3:05 a.m. on the 12th. During that time, its phase changes from waning gibbous to last quarter on the 8th, then to waning crescent.

The brilliant planet Jupiter is in Taurus the Bull and is noticeable in the east by midnight. At dawn, Jupiter is only 16 degrees southeast of the zenith, the point directly overhead. Steadily held binoculars are powerful enough to reveal Jupiter’s four largest moons. The last quarter moon will pass only a degree below Jupiter on the morning of Saturday, the 8th.

The brightest planet, Venus, rises in the east-northeast at 3:00 a.m. Venus is 32 degrees above the eastern horizon at dawn. A telescope will show the planet’s gibbous phase.

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 five days a week (Wednesday-Sunday) through Griffith Observatory’s telescopes before 9:30 p.m. Check our website for our schedule. The next Griffith Observatory public star party, hosted by Los Angeles Astronomical Society, the Sidewalk Astronomers, and the Planetary Society is scheduled for Saturday, September 22.

From Griffith Observatory, I’m Anthony Cook, and I can be reached at griffithobserver@gmail.com.