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This is the Griffith Observatory Sky Report through June 24, 2015. Here’s what’s happening in the skies of southern California.
Summer begins in the earth’s northern hemisphere at 9:38 a.m., PDT, on Sunday, June 21, the summer solstice. At the same moment, winter begins in the earth’s southern hemisphere. The summer solstice happens at the moment when the sun reaches its farthest point north of the celestial equator. At Los Angeles, the summer solstice sunrise and sunset occur 29 degrees north of east and 29 degrees north of west, respectively. This is the longest day of the year in the northern hemisphere, 14 hours and 26 minutes long at Los Angeles, with the local sunrise at 5:42 a.m. and sunset at 8:08 p.m. Summer will end and autumn begins on September 22, the autumnal equinox.
Special observances of the solstice will be held at Griffith Observatory on the 21st before local noon (12:55 p.m., PDT) at the meridian arc of the Gottlieb Transit Corridor, and at sunset (8:08 p.m., PDT) at the sunset and moonset radial lines engraved on the west walkway of the building. At Griffith Observatory, the sun will disappear behind the hills at 8:05 p.m. Explanatory talks by Observatory staff will start about 15 minutes before each event.
The brightest planet, Venus and the second brightest planet, Jupiter, make a dazzling sight in the western sky for nearly three hours after sunset. The moon will join the planetary grouping on Friday and Saturday, June 19th and 20th. Between the 17th and 24th, the angular separation between Venus and Jupiter decreases from 8 degrees to 3 degrees. The two planets are already visible together in the same field through low-power binoculars and will remain so through late July. Venus will appear closest to Jupiter on June 30th, when they appear only one-third of a degree apart.
Venus appears crescent through a telescope. This is because Venus is now closer to Earth than the sun, and we see less than half of its sunlit side. Between the 17th and 24th, the crescent wanes from 43-percent to 38-percent. At the same time the planet appears to grow from 27 to 30 arcseconds across.
Saturn, in Libra the Scales, is visible as a bright golden point in the southeast as darkness falls, and is highest in the south when it crosses the meridian at about 10:50 p.m. Saturn sets five hours later in the west-southwest. This is a great time to use a telescope to observe Saturn’s majestic ring system. Saturn and its rings are currently featured, as well as Venus, Jupiter, and the moon through Griffith Observatory’s public telescopes.
The waxing crescent moon appears low in the west-northwest after sunset on the 17th. It is half-lit, or first-quarter phase, on the morning of Wednesday the 24th. The time of moonset changes from 9:05 p.m. on the 17th, to 12:45 a.m. on the 24th.
Early-risers can start to see the planet Mercury on June 20. It will be 7 degrees above the east-northeast horizon at 5:12 a.m., the beginning of morning civil twilight. It is 2 degrees from the orange star Aldebaran of the constellation Taurus the Bull on the 24th, at which time Mercury outshines the star, slightly.
The International Space Station can best be seen over Los Angeles on Friday, June 19. The ISS will grow brighter than Jupiter while it moves from northwest to southeast across the sky, starting at 9:18 p.m., PDT. It will reach its highest, nearly overhead, at 9:21 p.m., then moves into Earth’s shadow while still 27 degrees above the horizon.
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, June 20.
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From Griffith Observatory, I’m Anthony Cook and I can be reached at griffithobserver@gmail.com