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This is the Griffith Observatory Sky Report through July 19, 2017. Here’s what’s happening in the skies of southern California.
The planet Mercury can be found beginning 30 minutes after sunset. The planet resembles a bright star about 10 degrees above the western horizon at that time, and it sets at 9:25 p.m. Ten degrees is the angular measurement of your clenched fist when viewed from arm’s length. The bright star Regulus in Leo the Lion is located to the upper left of Mercury by an angle that shrinks from 17 degrees to 7 degrees between the 12th and 19th. Mercury currently displays a gibbous phase when seen through a telescope.
The brightest object in the southwest sky during twilight is the giant planet Jupiter, in the constellation Virgo the Maiden. Jupiter can be observed until it sets in the west at midnight. In addition to its four largest moons that are bright enough to see through binoculars, Jupiter’s banded clouds and oval storms are fascinating to observe through a telescope. Jupiter’s most famous oval storm, the Great Red Spot, will be visible to west coast observers at 9:00 p.m. on the 14th, 16th, and 18th.
The golden-hued planet Saturn, in the constellation Ophiuchus the Serpent Bearer, is the brightest object in the southeast sky as darkness falls, and it is located about 13 degrees to the left, or east of, the bright orange star Antares in the constellation Scorpius the Scorpion. Saturn’s rings are beautiful through nearly any telescope. Saturn, as well as Jupiter and Mercury are all currently featured through the public telescopes at Griffith Observatory.
The moon rises nearly 40 minutes later from one night to the next, and it retreats to light only the early morning hours. Moonrise occurs at 10:33 p.m. on the 12th and at 2:22 a.m. on the 19th. During the same period, the moon’s phase changes from waning gibbous to waning crescent, and it is last quarter on the 16th.
The brightest planet, Venus, rises at 3:00 a.m., and is still visible in the east at sunrise. Venus currently displays a gibbous phase when seen through a telescope.
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, July 29th.
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From Griffith Observatory, I’m Anthony Cook, and I can be reached at griffithobserver@gmail.com.