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This is the Griffith Observatory Sky Report through September 14th, 2016. Here’s what’s happening in the skies of southern California.
Three bright planets and the Moon are well placed for observation shortly after sunset. Look west at 7:30 p.m. to see the brightest planet, Venus, close to the horizon. Venus is visible for another 45 minutes before it sets. Higher in the sky, toward the south-southwest, bright orange planet Mars can be seen to the lower left of the fainter, and golden, planet Saturn. Saturn is located above the orange star Antares of the constellation Scorpius the Scorpion. The eye-catching triangle formed by these three objects appears to change between the 7th and 14th. While the angular separation between Saturn and Antares remains about six degrees, the angular separation between Mars and Saturn will grow from 8 degrees to 14 degrees. The Moon changes phase from waxing crescent to waxing gibbous over the same period, and is first quarter on the night of the 8th, when it also appears close to Saturn in the sky. On the following night it appears next to Mars.
Through a telescope, Venus, appears small and gibbous in phase. Even though Venus is closer to the Sun than the Earth is, it is also on the far side of the Sun from Earth, so we now see mostly the daytime side of Venus. The disk of Mars shows an even more pronounced gibbous phase. Because the orbit of Mars is outside the Earth’s orbit, we never see the planet less than 85 percent illuminated. This is how Mars appears now. The ring system around the planet Saturn is one of the most astonishing sights visible through a telescope. Although Saturn is too far away to show a visible phase, a careful look at its rings will show the shadow cast by the planet onto the rings. The position and amount of the shadow visible changes with the relative position of Sun, Earth and Saturn, and currently the shadow, appearing as a small gap in the part of the ring that passes behind Saturn on the northeast side of the planet, is close to its maximum size.
The Moon is also a spectacular sight with almost any magnification with binoculars or a telescope. The most detail is visible along the Moon’s terminator, the region between the day and night portions of the Moon, where the long shadows cast by the waxing Moon’s craters and hills during the lunar sunrise emphasizes the Moon’s rugged relief. If you haven’t seen this for yourself, try looking!
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. Because of heavy traffic, we advise arriving in the afternoon! 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, September 10, between 2:00 p.m. and 9:30 p.m.
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From Griffith Observatory, I’m Anthony Cook and I can be reached at griffithobserver@gmail.com