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The Sky This Week, 2009 July 31 - August 24

Vacation time: Moon, Meteors, and Mars, Oh My!

“The Sky This Week” will be taking some time off for summer vacation during the month of August.  There’s a chance that if we can find a reliable Internet connection we can still do our weekly updates, but for now a monthly summary will have to do.

The Moon continues to wax in the evening sky as August opens.  The Full Sturgeon Moon occurs on the 5th at 8:55 pm Eastern Daylight Time.  Last Quarter occurs on the 13th at 2:55 pm, while New Moon falls on the 20th at 6:02 am.  There will be a virtually invisible penumbral lunar eclipse on the evening of the 5th.  Look for the Moon close to bright rising Jupiter on the evenings of the 5th and 6th.  The Moon mingles with Mars and Venus in the morning sky from the 15th through the 18th.

The annual Perseid meteor shower is scheduled to peak on the night of August 11th through 12th.  This is the “Old Faithful” of meteor showers, with records of its yearly return dating back nearly 2000 years.  It is characterized by swift, often bright meteors that can leave persistent trains in their wake.  Unfortunately the waning gibbous Moon drowns out all but the brightest members, so a late-night dedicated Perseid watch is probably not worth the usual effort.  However, during the night of peak activity, you should see a few bright meteors per hour, some of which may flash to the apparent brightness of Jupiter or Venus.  Brighter Perseid fireballs also often fragment in a so-called “terminal burst”, so try not to ignore them completely.  If we have a very clear night, by all means spend an hour or so outside after midnight to try to catch a few.  The shower is active at reduced strength from now until around August 22nd, so you’re bound to see at least one or two bright ones during that time!

August is the month for Jupiter to rise and shine.  The giant planet reaches opposition on the 14th, rising at sunset and setting at sunrise the following morning.  Jupiter lies in a very sparse starfield on the eastern fringes of the constellation of Capricornus, and during the month he slowly retrogrades westward to the north of the third-magnitude star Deneb Algeidi, the “Sea-Goat’s” tail.  Jupiter’s moons will be easy to spot in steadily held binoculars, and even a modest spotting scope should begin to show the planet’s dark equatorial cloud belts.  Amateur telescopes of four-inch or larger aperture should show more an more detail on the planet’s tortured cloud tops, as his apparent disc swells to nearly 50 arcseconds in apparent diameter.  The dark “scar” from a small-body impact on Old Jove is still visible near the planet’s south pole, and while it is elongating in the screaming jet streams in Jupiter’s atmosphere it may persist for a few more weeks.  See if you can spot it before it fades completely.

Sunrise is now slowly creeping later each passing morning, and seemingly trying to chase down the rising Sun is bright Venus.  The dazzling planet spends the month transiting the stars of Gemini, while fainter ruddy mars lags behind traversing the stars of Taurus.  As we near the astronomical middle of the summer season on August 7th, you’ll find the stars of winter beginning to greet you in the gathering morning twilight.  By the 21st you’ll see the bright stars of Orion stepping over the horizon as dawn gathers.

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