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This is the Griffith Observatory Sky Report for the week ending Wednesday, September 25, 2013. Here is what’s happening in the skies of Southern California:
Summer ends and autumn begins at 1:44 p.m., P.D.T. on Sunday the 22nd. Known as the autumnal equinox, the event marks the sun’s southbound crossing of the celestial equator, the projection of earth’s equator into space. Equinox means “equal night”, and following the autumnal equinox, northern hemisphere nights become longer than its days. The autumn season ends with the winter solstice, on December 21. Free public equinox observances will be held on the grounds of Griffith Observatory on the 22nd. The first will take place on the southwest side of the grounds at the Gottlieb Transit Corridor starting at 12:30 p.m. At 12:46 p.m., the sun will pass through Griffith Observatory’s local meridian. The sun’s meridian crossing will be projected on the meridian arc and star chart of the transit corridor. Another gathering, at the west walkway of the building, takes place at 6:30 p.m. to observe the sunset at 6:43 p.m. The sunset will then align with the solstice sunset line engraved into the Observatory’s west walkway. Both events will be lead by the Observatory’s Astronomical Lecturer, Dr. David Reitzel.
The brightest planet, Venus, is three degrees south of the ringed planet, Saturn, on Wednesday the 18th. Venus is visible in the southwest even before sunset. Saturn becomes noticeable about half an hour after sunset. On following evenings, Saturn moves to the right of Venus, and is separated from the brighter planet by more than 8 degrees on the 25th. The two planets set in the west-southwest at 8:40 p.m.
Full moon is on the night of the 18th, and occurs precisely at 4:13 a.m., P.D.T. on the 19th. This is the Harvest Moon, and it is celebrated as such by many cultures. On the nights around the full moon close to the start of autumn, moonrise happens about 40 minutes later on successive evenings from our latitude (34 degrees north), the minimum for the year. Before the era of artificial lighting, farmers found the bright moonlight after sunset useful for extending harvest work into the night. By Tuesday the 24th, the waning gibbous moon will rise at 10:22 p.m., P.D.T., well after darkness falls. Griffith Observatory will provide a telescope for free public moon viewing during the Los Angeles Chinatown annual Moon Festival on Saturday night, the 21st.
The second brightest planet, Jupiter, is in Gemini the Twins and rises above the east-northeast horizon at 1:00 a.m. Orange Mars, in Cancer the Crab, follows more than two hours later, and is located 28 degrees to the lower left of Jupiter. Jupiter is 51 degrees high in the east-southeast at the start of dawn, and Mars is half as high in the east at the same time.
The planned launch of a Canadian research satellite called Cassiope aboard an all-new version of the SpaceX Falcon 9 from Vandenberg Air Force base has been delayed until the last days of September. Details about the launch and how to watch it may appear in next week’s Sky Report.
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 Tuesday-Sunday before 9:30 p.m. Check our website for our 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, October 12.
From Griffith Observatory, I’m Anthony Cook and I can be reached at griffithobserver@gmail.com.