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This is the Griffith Observatory Sky Report through May 10th, 2017. Here’s what’s happening in the skies of southern California.
The moon’s phase is waxing gibbous until it reaches full on the 10th. No object in the sky shows more telescopic detail than the moon. Use binoculars or a telescope to watch the gradually changing view as new features appear along the slowly moving line, called the terminator, that divides the moon’s day and night sides. Because even small irregularities on the moon’s surface are exaggerated by the grazing sunlight that reaches the terminator, the terminator presents the most fascinating detail to observers. On the 3rd, the terminator will cross the moon’s Apennine mountain range, which is the raised edge of a giant lava-filled asteroid impact scar called an impact basin. On the 5th, the 64 mile-wide crater Copernicus will be dramatically lit on the terminator. When the moon is full on the 10th, the shadows cast by lunar features will all be turned away from us, so only lunar brightness differences are visible, but the moon’s rugged texture is hidden. The moon is one of the objects featured through Griffith Observatory’s public telescopes through the 10th.
The second brightest planet, Jupiter, blazes in the southeast sky shortly after sunset. Located against the stellar backdrop of the constellation Virgo the Maiden, Jupiter is at its highest, 51 degrees above the southern horizon, at about 11:00 p.m., and it sets in the west shortly before dawn. Binoculars can reveal Jupiter’s four largest moons, but a more powerful telescope is needed to reveal the wealth of detail present in the striped cloud belts of the giant planet. Jupiter’s famous oval storm, the Great Red Spot, will face observers on the west coast at 9:00 p.m. on the 3rd, 5th, and 8th. The moon appears close to Jupiter in the sky on the 6th and 7th. Jupiter and its moons are also currently featured through Griffith Observatory’s public telescopes.
The planet Saturn appears golden and star-like in the constellation Sagittarius the archer. It is visible above the east-southeast horizon by 11:00 p.m. and crosses the meridian, 35 degrees above the southern horizon before 4:00 a.m., then moves to the southwest during the dawn. Saturn and its rings are spectacular through nearly any telescope.
The brightest planet, Venus, rises at about 4:00 a.m. It is brilliant in the east-northeast until sunrise. Venus displays a crescent phase when seen through telescopes.
Although comet Halley will not be for visible another 44 years, pieces of the comet will flash in the eastern sky before dawn this weekend. The Eta Aquaiid meteor shower is visible from 3:00 a.m. until the start of dawn, at 4:25 a.m., on the mornings of May 5th and 6th. Conditions for observing the shower are best after moonset, which happens at 3:19 a.m. on the 5th and 3:54 a.m. on the 6th. The meteors appear to stream from the “Water Jar” of Aquarius the Water Bearer, located in the east-southeast. The meteor stream consists of particles shed centuries ago by comet Halley. From a dark wilderness location in southern California, about 20 Eta Aquariid meteors may be seen per hour, about half the rate visible to observers located in the tropics.
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, May 6th from 2:00 p.m. until 9:30 p.m.
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From Griffith Observatory, I’m Anthony Cook, and I can be reached at griffithobserver@gmail.com.