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This is the Griffith Observatory Sky Report through October 7, 2015. Here’s what’s happening in the skies of southern California.
The planet Saturn is the only bright planet visible in the early evening, and only for a short time after sunset. Located in the constellation Libra the Scales, Saturn appears like a bright golden star in the southwest sky at twilight. Saturn sets in the west-southwest at 9:20 p.m. on September 30 and 4 minutes earlier each following night. There still is a chance to see Saturn’s magnificent rings through a telescope if you start early!
Now past the Harvest perigee full moon and lunar eclipse, the waning moon rises well after darkness falls. This week the moon rises about 50 minutes later from one night to the next, and between September 30 and October 7, its rising time advances from 10:53 p.m. to 2:10 a.m. Its phase changes from gibbous to last quarter on the 4th, and is crescent until the next new moon on October 12.
The moon will cover, or occult, the bright orange star Aldebaran, of the constellation Taurus the Bull, shortly before sunrise on Friday, October 2. Because the sky will be bright then, binoculars, or even better, a telescope, will be needed to see the star suddenly wink out when it its covered by the center of the bright limb of the gibbous moon at 6:39 a.m. Only a telescope will be able to show the equally abrupt re-appearance of Aldebaran from behind the center of the unlit limb of the moon at 7:15 a.m., about 16 minutes after sunrise. Centuries before the space age, the lack of fading of stars and their abrupt disappearances and reappearances during occultations by the moon, informed astronomers that the moon has no significant atmosphere.
The brightest planet Venus, rises over the eastern horizon at 3:25 a.m., and the second brightest planet, Jupiter rises at 4:40 a.m. At 6:20 a.m., about 30 minutes before sunrise, Venus is 36 degrees high in the east-southeast. Jupiter is about 15 degrees to the lower left of Venus, midway between Venus and the horizon. Two other objects are visible to the lower left of Venus, above the imaginary line connecting Venus and Jupiter. The upper object is bright star Regulus of the constellation Leo the Lion, and the fainter red object is the planet Mars, on the far side of its orbit from us and appearing relatively faint. Notice how all four objects move relative to one another from morning to morning.
The International Space Station, the orbital research station for six astronauts and cosmonauts of different countries, will make two appearances over Los Angeles. On Friday night, October 2, The ISS will appear over the south-southwest horizon at 7:35 p.m., PDT and will appear at its highest outshining anything else then in the sky while 52 degrees over the southeast horizon, three minutes later. The ISS will fade into Earth’s shadow at 7:40 p.m. while it is still 26 degrees high in the north-northeast. On Sunday, October 4, the ISS will cross the sky from west-southwest to the northeast between 7:27 p.m. and 7:34 p.m., PDT, and attains a maximum elevation of 50 degrees in the northeast at 7:30 p.m.
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, October 17.
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From Griffith Observatory, I’m Anthony Cook and I can be reached at griffithobserver@gmail.com