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The Sky This Month, 2011 July 27 - August 23

Celestial sights for summer vacation.

The "Sturgeon Moon" Rising
Imaged 2008 August 17, Fishers Island, NY

"The Sky This Week" will be on vacation for the next few weeks, so in its place we’ll post some celestial highlights to look for over the course of the next month. Of course, if something unusual occurs or an interesting discovery is made, we’ll do our best to update from the road.

New Moon occurs on July 30th at 2:40 pm Eastern Daylight Time. First Quarter falls on August 6th at 7:08 am. August’s Full Moon, popularly known as the Green Corn Moon, Grain Moon, or Sturgeon Moon, occurs on the 13th at 2:57 pm, with Last Quarter occurring on the 21st at 5:54 pm. Luna passes well south of Saturn on the evening of the 3rd. On the following evening she may be found just south of the bright star Spica. She lies between the ruddy star Antares and the stars that form the "head" of Scorpius on the night of the 7th, while on the night of the 9th she hangs just above the "Teapot" asterism of Sagittarius. From there she moves into the sparse reaches of the rising autumnal constellations. On the 19th she rises at around 11:00 pm in the company of bright Jupiter.

August 1st is Lammas, one of the traditional "cross-quarter" days of the ancient Celtic calendar. Traditionally this date marked the middle of the summer season and was the first of several harvest festivals celebrated in medieval northern Europe. Today it is the only cross-quarter day that is not observed in some form in the English-speaking world. Don’t fear that summer is almost gone, though, since the actual mid-point of the season falls one week later on August 7th.

This year’s Full Moon will all but wipe out the annual Perseid meteor shower, which happens to peak on the same night. Fortunately the Perseids are known for producing a good number of bright swift meteors as well as a few fireballs, and the activity starts building as August opens. The best times to observe are after local midnight, when the radiant constellation of Perseus begins to climb in the northeastern sky. Moonlight shouldn’t become a big factor for early morning observations until after the 9th or 10th.

The month of August will also feature a "changing of the guard" as far as bright evening planets are concerned. Saturn remains visible for most of the month in the southwestern sky and is best seen during the fading light of evening twilight. This makes it increasingly difficult to spot his fainter moons, but his signature rings and brightest moon Titan should be easy to spot once you locate the planet in the telescope. Shortly after Saturn sets the bright glow of Jupiter will appear on the eastern horizon. The giant planet rises shortly after midnight as August opens, and by the 20th he comes up at around 11:00 pm. You’ll have no trouble spotting his four large Galilean moons once he’s well clear of the treeline. They can be seen with a steadily held pair of binoculars and are a spectacular sight in even the smallest of telescopes. The last of the visible planets, faint ruddy Mars, plies his way from the "horns" of Taurus, the Bull to the middle of the Gemini twins over the course of August. The red planet is best seen just as morning twilight begins to brighten the eastern sky.

If you happen to be on vacation near the ocean, mountains, or anywhere well away from city lights, take advantage of the days before lunar First Quarter or after last Quarter to enjoy one of the most spectacular sights in all of Nature, the summertime Milky Way. At midnight this band of ghostly light divides the sky in two as it runs from the northeast to the southwest. From dark locations you can easily spot patches of brightness along with knots of interspersed darkness. In particular look for the "Great Rift" that cleaves the galaxy in two from the center of the Summer Triangle down to the southern constellations of Scorpius and Sagittarius. Use your binoculars to sweep through the magnificent star clouds just above the "spout" of the Sagittarius "teapot" or piercing the middle of the Summer Triangle. I often spend hours with my small low-power wide-field telescope just gazing in awe at the innumerable stars in these regions. I can’t think of a more relaxing way to spend a clear summer evening than being lost in that immensity.

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