This is the Griffith Observatory Sky Report through September 23, 2015. Here’s what’s happening in the skies of southern California.
The waxing moon lights the evening sky for a longer and longer time each passing night, setting at 9:00 p.m. on the 16th and 1:42 a.m. on the 23rd. The moon is crescent before it reaches first quarter phase on the 21st, and then is gibbous before it reaches full, and is totally eclipsed, on the 27th. Details of the lunar eclipse are given on our eclipse web page and will be the discussed in the next Sky Report. The moon is featured in Griffith Observatory’s public telescopes this week.
If you haven’t tried this already, aim your binoculars at the moon. With them you can see many of its features, including especially the craters, and its broad, dark, dusty lava plains. Keep your binoculars handy to see the beautiful colors of the upcoming eclipse.
The only bright planet in the early evening is golden Saturn, in Libra the Scales. It is located in the southwest sky during evening twilight. Saturn sets in the west-southwest at about 10:00 p.m. The moon is two degrees north of Saturn on the 18th. Binoculars may show you that the planet has an elliptical appearance, but a more powerful telescope is needed to see that this is caused by Saturn’s spectacular rings.
Three planets can be seen above the eastern horizon during the dawn, at 6:00 a.m. The brightest of them, Venus, is also the highest, and is then nearly 30 degrees high. The second-brightest planet, Jupiter, is also the lowest, about a third as high as Venus. Between Jupiter and Venus is a bright white star, Regulus, of Leo the Lion. Regulus can help you to spot the planet Mars, which can be found above Regulus, closing in from 5 degrees to only one degree of the star between the 16th and 23rd. Red hued Mars is now distant from Earth, on the far side of the sun, but will nearly equal Jupiter’s brilliance at it’s next close approach to Earth this coming May. A telescope will show the crescent phase of Venus, and the disk and four bright moons of Jupiter, but Mars is too small and far away to see details right now.
Autumn begins in Earth’s northern hemisphere at 1:21 a.m., PDT on the 23rd, and is also known by the astronomical term, autumnal equinox. Spring begins in the southern hemisphere at the same time. “Equinox” means “equal night” and refers to the fact that because the sun is then directly overhead at noon on the equator, nights and days are of nearly equal length over almost the whole Earth. Autumn ends with the winter solstice on December 21.
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 firstname.lastname@example.org