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This is the Griffith Observatory Sky Report through October 11, 2017. Here’s what’s happening in the skies of southern California.
The planet Saturn appears similar to a bright, golden star as it temporarily visits the constellation Ophiuchus the Serpent Bearer, and it is prominent in the southwest sky when darkness falls. On the 6th, Saturn’s beautiful system of rings, visible through nearly any telescope, display their greatest tilt for the next 15 years – 26.966 degrees from edge-on, enough for the outer edge of the ring’s ellipse to enclose the ball of the planet easily. Saturn sets in the west-southwest at 10:23 p.m. on the 4th and at 9:58 p.m. on the 11th, and it will soon move out of the evening sky. This is the last week this year to catch a view of Saturn and its rings through the public telescopes at Griffith Observatory.
The more observationally challenging outer planets, Uranus and Neptune, are well positioned for viewing through telescopes later in the evening. Neptune, in the constellation Aquarius the Water Bearer, is best placed for scrutiny when it crosses the meridian at about 10:30 p.m.
Uranus, in Pisces the Fishes, crosses the meridian about 2 ½ hours after Neptune. The planets can be identified through most telescopes at high magnification by each planet’s tiny disk, that of Uranus with a pale-green hue and Neptune’s with a ghostly blue tint. If your telescope does not automatically point itself at the planets, try using the detailed finder charts, available on the Sky and Telescope Magazine Website.
Early Thursday night, October 5th, telescope-equipped observers on the East Coast will be able to see a rare occultation of a 12th magnitude star by Neptune’s largest moon, Triton. From Europe, the event is also visible, although there it occurs in the early hours of October 6th. How Triton and its tenuous atmosphere cause the star to dim should reveal important scientific information about the Pluto-sized world. Detailed information about the event is linked to another special Sky and Telescope Webpage.
The moon is full between the nights of the 4th and 5th, when it rises at about sunset. Because this is the first full moon to occur after the fall equinox, its rising time changes little for several nights while it is close to full, and is widely known as the harvest moon due to it’s utility as a work light to farmers in the era before electricity. Communities worldwide, including those in Los Angeles, will celebrate the traditional Asian Harvest Moon or Mid-Autumn Moon Festival on the weekend. By the 11th, when the moon is still waning gibbous, moonrise happens at 11:42 p.m.
A west coast launch of a SpaceX Falcon 9 rocket from Vandenberg Air Force Base, California, has been re-scheduled to Monday morning, October 9, at 5:37 a.m. From Los Angeles, look to the west to see the rocket arc up and toward the south in the pre-dawn sky. Use binoculars to look for the re-ignition of the rocket’s first stage as it begins to maneuver for its planned landing on a barge in the ocean, while the rocket’s second stage carries the payload of 10 Iridium Next communication satellites to orbit. Live streaming coverage and notification of schedule changes will be available on the SpaceX Webpage.
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. 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 21st.
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From Griffith Observatory, I’m Anthony Cook, and I can be reached at griffithobserver@gmail.com.