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This is the Griffith Observatory Sky Report through May 20, 2015. Here’s what’s happening in the skies of southern California.
The brightest planet, Venus, is the brilliant object in the western sky from sunset until 11:15 p.m. A telescope will show Venus as gibbous, about 60-percent illuminated.
Venus can help you to find the innermost planet, Mercury. At 8:15 p.m., the sky should be dark enough to pick out Mercury. It will resemble a bright star, below and a little to the right of Venus, and ¼ as high as Venus. A telescope can show Mercury’s narrow crescent phase.
The second brightest planet, Jupiter, is in the constellation Cancer the Crab, and is high in the southwest sky in evening twilight. Jupiter and Venus are drawing closer together in the sky at the rate of a degree per day, and will have a spectacular conjunction on June 30. Between the 13th and the 20th of this month, their separation shrinks from 38 to 31 degrees. Mercury, Venus, and Jupiter are currently featured through Griffith Observatory’s public telescopes.
The ringed planet, Saturn is in the constellation Libra the Scales. The planet resembles a bright, golden star in the southeast after it rises at 8 p.m., and is best placed for viewing in the south, at 1:30 a.m. Use a telescope to see Saturn’s spectacular ring system.
The moon is waning crescent in the morning sky until the 17th. It is new that night, and moves to the evening sky as a waxing crescent, below Venus and near the horizon, starting on the 19th.
Moonset on Tuesday the 19th happens at 9:32 p.m., PDT, and is a rare minor lunar standstill moonset. When the moon sets, it will align with a special marker permanently engraved into the western walkway outside the Observatory. As seen from Los Angeles, the tilt of the moon’s orbit around the earth causes the maximum that the moon can rise or set from east or west, respectively, to change from as little as 22 degrees north or south to as much as 35 degrees north and south over a 9.3 year time span. This year, the maximum that moonrises and moonsets stray from east or west is 22 degrees, the minimum possible value, and these moonrises and moonsets are called minor lunar standstills. The term ‘standstill’ is used because the direction that the moon rises or sets changes very little for two or three nights when it is close to its extreme value, north or south. The minor standstill moonset of May 19 is the only standstill event visible during nighttime operating hours from Griffith Observatory until the major standstill moonsets of 2024. Members of the Observatory staff will be present on Tuesday, starting at 9:15 p.m., to point out the marker and the minor standstill moonset.
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 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, May 30.
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.