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This is the Griffith Observatory Sky Report through September 28th, 2016. Here’s what’s happening in the skies of southern California.
Autumn begins at 7:21 a.m., PDT on Thursday the 22nd – the autumnal equinox. Spring begins in the southern hemisphere at the same time. The autumnal equinox is the moment when the sun, moving south, crosses the celestial equator–the projection of the earth’s equator into space. Events on the 22nd that will allow you to observe the effects of the changing season will be held at Griffith Observatory’s Gottlieb Transit Corridor shortly before local noon (12:46 p.m.), and at the inscribed lines on the west walkway of the Observatory before sunset (6:49 p.m.). Autumn ends with the winter solstice on December 21st.
The planet Venus is the first to appear after sunset, and appears as an intensely bright point above the western horizon until it sets at about 8:00 p.m. A telescope shows the cloud-covered planet as a featureless, tiny white globe with a gibbous phase.
The planet Saturn, shining in the southwest, and brighter planet Mars, to the lower left of Saturn in the south-southwest sky, are the most noticeable objects in that part of the sky as it darkens. The twinkling orange star below Saturn is Antares, the brightest star in Scorpius the Scorpion. Mars is too far away to show detail through most telescopes, but the rings of Saturn are spectacular, and are among the objects featured through Griffith Observatory’s public telescopes.
The phase of the Moon wanes from gibbous to crescent between the 21st and 28th, and is last quarter on the morning of the 23rd. The time of moonrise over this period advances from 12:02 a.m. to 6:21 a.m.
The planet Mercury is best seen at the end of nautical twilight, which happens at about 6:20 a.m. It will then be due east and 10 degrees above the horizon. Ten degrees is the angle roughly equal to what your clenched fist measures when seen at arm’s length.
The International Space Station will make three visible passes high over Los through the 28th. The first happens on Thursday morning, the 22nd, between 6:08 a.m. and 6:15 a.m., PDT as the brilliant space station crosses the sky from the northwest to the southeast, and is high overhead at 6:12 a.m. On the following morning, September 23rd, the ISS can be seen between 5:18 a.m. and 5:23 a.m. as it moves from the north-northwest to the east-southeast. The ISS is highest, 48 degrees above the northeast horizon, at 5:23 a.m. A spectacular evening appearance will occur on Tuesday the 27th. The brilliant satellite will appear above the southwest horizon at 8:02 p.m., PDT, and will appear overhead three minutes later. A few seconds after that, the ISS will fade into Earth’s shadow while still 61 degrees high in the east-northeast.
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, October 8th.
Follow the Sky Report on Twitter for updates of astronomy and space-related events.
From Griffith Observatory, I’m Anthony Cook and I can be reached at griffithobserver@gmail.com