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This is the Griffith Observatory Sky Report through June 27, 2018. Here’s what’s happening in the skies of southern California.
Summer begins in the earth’s northern hemisphere on the solstice, which happens on the 21st, at 3:07 a.m., PDT. The solstice is the moment when the sun reaches its farthest point north of the celestial equator. The June solstice is the northern hemisphere’s longest day; at Los Angeles, the sunrise is at 5:42 a.m., and it sets at 8:08 p.m., so there are 14 hours and 26 minutes of daylight. This solstice also marks the start of winter in the southern hemisphere. The season ends with the start of northern autumn at the equinox on September 22nd.
As if the long summer day doesn’t do enough to shorten the night, the moon chips away at the dark hours through the 27th because its phase waxes from first quarter to full in this period. Between the 20th and the 27th, its setting time advances from 1:09 a.m. to 5:25 a.m.
The brightest planet, Venus, is easy to see in the northwest sky as soon as the sun sets. Venus can be seen until it slips below the horizon at 10:40 p.m. Through a telescope, Venus now shows a gibbous phase about 74 percent illuminated. This resembles the moon’s appearance to the unaided eye about five days from full.
Also prominent in the evening twilight, the second brightest planet Jupiter–in Libra the Scales–gleams in the southeast sky. Jupiter is highest in the southern sky when it crosses the meridian at 9:30 p.m. After that, Earth’s rotation gradually carries it to the west-southwest horizon at about 3:00 a.m. A telescope may allow you to see the planet’s famous oval storm, the Great Red Spot, when it is on the side of Jupiter facing west coast observers, as it will be at 9:00 p.m., PDT on the 22nd and 24th. The gibbous moon is close to Jupiter on the 22nd and 23rd.
The ringed planet, Saturn, in the constellation Sagittarius the Archer, is directly opposite to the sun in the sky–at opposition–during the night of the 26th. On that night, it rises at sunset, appears highest in the south at 12:57 a.m. on the 27th, and sets at sunrise. It is then at its closest point to us for the year, 837 million miles, or the distance that light travels in 75 minutes. As seen through a telescope, the alignment between the sun, the Earth, and Saturn make the rings brighten dramatically for several days around opposition, a phenomenon known as the Sieliger effect. Usually, Saturn’s rings look about as bright as the planet itself. For a few days around opposition, however, the rings will clearly appear brighter than the planet. The Sieliger effect happens when the particles hide the view of their shadows on other particles when the observer is looking from the direction of the sun. The moon appears near Saturn in the sky on the 28th.
The orange planet Mars, in Sagittarius the Archer, appears as bright as Jupiter, and is eye-catching in the southeast sky by 11:00 p.m. The planet is best positioned for observing through a telescope at its meridian transit, when it appears at its highest in the south. The transit occurs at about 3:30 a.m. In about five weeks, Mars will be at its closest to Earth since 2003. A large dust storm that broke out at the end of May has covered more than half of the planet in thick dust, hiding many of the Martian telescopic features.
The asteroid 4 Vesta is now at its brightest in Sagittarius, only about 8 degrees to the west (right) of Saturn. Vesta now appears like a star of magnitude 5.3, or just bright enough to see from a dark wilderness location with your unaided eyes! The Heavens-Above Website has a Vesta finder-chart generator that will create charts that may help you to find the bright asteroid through a small telescope, binoculars, or from a very dark sky, just with your eyes.
Free views of the Sun during the day and of the moon and planets 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, June 23rd, between 2:00 and 9:30 p.m.
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From Griffith Observatory, I’m Anthony Cook, and I can be reached at griffithobserver@gmail.com.