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This is the Griffith Observatory Sky Report through September 2, 2015. Here’s what’s happening in the skies of southern California.
The moon brightens the night, changing from waxing gibbous to full on Saturday, August 29, then to waning gibbous through September 11. Moonrise happens after sunset starting on August 29. The time of moonrise changes from 7:25 p.m. to 10:15 p.m. between August 29 and September 2.
The innermost planet, Mercury, can be spotted about 6 degrees above the west point of the horizon for a short time starting about 30 minutes after sunset. For comparison, your clenched fist appears about 10 degrees high when viewed at arm’s length. Binoculars will help you to see the planet against the brightness of the twilit sky.
The brightest evening planet is Saturn, in the constellation Libra the Scales. Saturn stands out in the southwest sky as twilight deepens, and shines (actually reflects sunlight) with a bright, steady golden hue. A telescope is needed to see Saturn’s spectacular rings, and several of the planet’s moons. Saturn will be visible through the public telescopes at Griffith Observatory for about three more weeks.
Neptune, the most distant planet of the solar system, is visible the entire night of August 31-September 1. That night, the planet is in opposition, the place in its orbit where it is opposite the sun in the sky as seen from Earth. Located in the direction of Aquarius the Water Carrier, Neptune rises at sunset, sets at sunrise, and is best placed for observation at about 1:00 a.m. Because it is three billion miles away, Neptune appears through a telescope as a tiny blue-grey spot. Although it is not difficult to see through a telescope, finding it is a challenge. If you don’t have a “go-to” computerized telescope that automatically points at Neptune, you will need a detailed star chart to identify it. Sky and Telescope’s website features a finder chart for Neptune.
As dawn brightens the morning sky, the brightest planet Venus appears near the fainter, red hued planet Mars. On the morning of September 1, Mars is 8 degrees to the left of Venus.
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, September 19.
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From Griffith Observatory, I’m Anthony Cook and I can be reached at griffithobserver@gmail.com