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This is the Griffith Observatory Sky Report through November 15, 2017. Here’s what’s happening in the skies of southern California.
The innermost planet, Mercury, should come out of the glare of the sun beginning on the 12th. If the air is clear, Mercury will resemble a bright star and will be found only 5 degrees above the southwest horizon at 5:17 p.m., the end of civil twilight, and then it sets about 30 minutes later. For comparison, remember that the angular height of your clenched fist as seen from arm’s length is about ten degrees. On following evenings through the 24th, Mercury will appear slightly higher in the sky and, therefore, it will become somewhat easier to find on subsequent dates.
Just as the sky darkens enough to reveal Mercury, the planet Saturn may be found about 20 degrees above the southwestern horizon. Saturn is currently in the constellation Ophiuchus the Serpent-Bearer. Saturn sets in the west-southwest at about 7:00 p.m.
By 11:00 p.m., the brightest nighttime star, Sirius, in the constellation Canis Major the Large Dog, is sparkling above the east-southeastern horizon. Sirius crosses the southern meridian at about 3:00 a.m., and begins to descend to the southwest by dawn.
The phase of the moon changes from waning gibbous to waning crescent between the 8th and 15th, and it is last quarter on the 10th. The time of moonrise advances from 9:36 p.m. to 3:42 a.m. over the same period. The moon appears close to the bright star Regulus in the constellation Leo the Lion on the morning of Saturday, the 11th. Later that morning, more than two hours after sunrise, you may be able to see the moon cover Regulus for more than an hour, but only with the aid of a telescope. This type of event is called a stellar occultation. The star is occulted by the moon’s illuminated edge at 8:51 a.m. and the occultation ends when the star reappears from behind the moon’s dark edge at 10:00 a.m., as seen from Los Angeles. A special web page of the International Occultation Timing Association, known to astronomers as IOTA, gives observing information for other locations along the occultation path that stretches from Japan and China to Central America and Cuba.
Because of its current position in space on the far side of its orbit from us, Venus appears to be drawing closer to the sun morning by morning, and as a result, its rising time changes from 5:07 a.m. on the 8th, to 5:21 a.m. on the 15th. The planet Mars, also currently close to its maximum distance from us, appears as an orange dot in the constellation Virgo the Maiden, and is 20 degrees above and slightly to the right of Venus.
On the 10th, the planet Jupiter, which is also emerging from the glare of the sun, should be obvious only three degrees below Venus. On the morning of Monday the 13th, Jupiter and Venus will create a spectacular pair of brilliant objects, separated by only 20 arcminutes, or two-thirds the apparent width of the moon. Both planets – and Jupiter’s four Galilean moons – will fit into a single eyepiece field-of-view.
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, November 18th.
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From Griffith Observatory, I’m Anthony Cook, and I can be reached at griffithobserver@gmail.com.