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This is the Griffith Observatory Sky Report through July 18th, 2018. Here’s what’s happening in the skies of southern California.
All of the bright planets that are easily visible to the unaided eye can be observed in the first half of the night.
Venus, the brightest planet, can be seen in the western sky at sunset, or even before sunset on very clear days. Half an hour after sunset, look for the innermost planet, Mercury, between Venus and the northwest horizon. Mercury will appear similar to a bright star against the twilit sky. There is also bright star that appears close to Venus now. It is Leo the Lion’s bright star, Regulus. Don’t confuse the star with Mercury, which lies in the same direction from Venus as Regulus, but closer to the horizon. Mercury sets at about 9:20 p.m., and Venus sets about an hour later.
Brilliant Jupiter, in the constellation Libra the Scales, is visible in the southern sky during the evening twilight, and sets in the west-southwest at about 1:15 a.m. Saturn, in Sagittarius the Archer, is visible to the left of Jupiter in the southeastern sky during evening twilight. It crosses the meridian in the south at about 11:25 p.m. Before dawn, it moves to the southwest sky, and sets at about 4:25 a.m.
The orange planet Mars, in the constellation Capricornus the Sea Goat, now outshines Jupiter and is the second brightest planet. It first becomes visible in the east-southeast at about the same time Mercury sets in the west-northwest. Mars is eye-catching as it moves higher in the sky. It reaches its highest in the south at about 2:00 a.m. Mars is still above the horizon, in the southwest sky, at sunrise.
A small telescope, used at high magnification, should be able to show the current crescent phase of Mercury and gibbous phase of Venus. Jupiter shows its four largest moons, its banded pattern of clouds, and its colorful oval storm, the Great Red Spot. The Great red Spot will face telescopes on the west coast at 9:00 p.m. on the 11th, 13th, 16th, and 18th. Saturn’s spectacular rings are perhaps the most memorable first sight through any telescope.
Mars, best observed through telescopes when it is highest in the sky between 1:00 a.m. and 3:00 a.m., may show a nearly blank amber-colored disk, because most of its features are currently hidden by a planet-wide dust storm that broke out at the end of May. Experienced observers with access to a telescope of 8-inches or more aperture may want to look for Phobos and Diemos, the rapidly orbiting moons of Mars. The Ring-Moon Systems Node On-Line Mars Planet Viewer by the SETI Institute can generate custom finder maps of the moons.
Our moon is new on the 12th, and it then causes a partial solar eclipse, visible only from the Eastern-Hemisphere coast of Antarctica, from where only about a third of the sun’s face will appear to be covered by the moon. The moon will become visible in the evening sky at Los Angeles on the 14th, when it is positioned to the right of Mercury. The moon passes close to Venus on the 15th, and it moves to the upper right of Jupiter on the 18th.
Free views of the Sun during the day and of the moon and planets at night are normally available to the public in clear weather through Griffith Observatory’s telescopes from Tuesday through Sunday, before 9:30 p.m. In the aftermath of a brush fire in Griffith Park, Griffith Observatory will be closed through Friday, July 13th. Check our website for the schedule and to confirm that the Observatory is open before you plan to visit. 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 21st.
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From Griffith Observatory, I’m Anthony Cook, and I can be reached at griffithobserver@gmail.com.