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This is the Griffith Observatory Sky Report through July 5th, 2017. Here’s what’s happening in the skies of southern California.
The moon’s illumination increases nightly. Its phase waxes from crescent to first quarter on June 30th, and afterwards it is gibbous until it reaches full on July 8th. Moonset advances from 11:56 p.m. on June 28th to 3:21 a.m. on July 5th.
As the evening darkness falls, the brilliant planet Jupiter, in the constellation Virgo the Maiden, is located midway up in the southwest sky. Use a telescope to see Jupiter’s famous oval storm, the Great Red Spot. The Great Red Spot faces West Coast observers at 9:00 p.m. on June 29th, July 2nd and July 4th. The moon appears close to Jupiter on Monday, July 3rd.
The planet Saturn, in Ophiuchus the Snake-Bearer, is paler than Jupiter, but at nightfall it is still the brightest object gleaming low in the southeast sky. Saturn is at its highest in the south at midnight, then it sets gradually in the west-southwest before sunrise. Saturn’s rings are visible through nearly any telescope. Now tilted nearly 27 degrees from edge-on, the rings are as broadly open to our view as they ever are. Although their tilt changes only slightly year by year, the rings will not again appear as open to us until the year 2032. The moon, Jupiter, and Saturn are all currently offered for viewing through Griffith Observatory’s public telescopes.
The planet Venus is visible in the east at dawn, and it outshines all astronomical objects after the sun and moon. Through a telescope, Venus displays a gibbous phase.
The Earth is at aphelion, its farthest point from the sun, on Monday, July 3rd at 1:11 p.m. PDT. The center of our planet then be 94,505,897 miles from the center of the sun, according to the NASA Horizons on-line ephemeris. This is 1,550,090 miles farther than the average separation between the two bodies. The precise values of the aphelion and the perihelion, (the least distance between Earth and sun), changes slightly from year to year because of the varying position of Earth around the center of gravity, or barycenter, of the Earth-moon pair, and to a lesser extent, because of the gravitational attraction of the other planets.
The International Space Station will rival Venus in brightness as it sails above Los Angeles at dawn on the 3rd. The ISS will cross the sky from the south-southwest to the northeast between 5:04 and 5:11 a.m., and it reaches highest point, 57 degrees above the southeast horizon, at 5:07 a.m.
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, happens on Saturday, July 29th.
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From Griffith Observatory, I’m Anthony Cook, you can reach me at griffithobserver@gmail.com.