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The Sky This Week, 2011 September 27 - October 4

Longer nights lead to starry delights.

Jupiter and its moon Io, 2011 August 12, 08:37 UT 
Imaged from Fishers Island, New York

The Moon returns to the evening sky this week, waxing through her crescent phases as she skirts the southern horizon among the setting summertime constellations. First Quarter occurs on October 3rd at 11:15 pm Eastern Daylight Time. Look for Luna’s fattening crescent a few degrees above the bright star Antares on the constellation Scorpius on the evening of October 1st. Over the course of the next few nights she crosses the heart of the summertime Milky Way as she drifts through the stars of the "Teapot" asterism of the constellation Sagittarius.

The first full week of autumn finds the nights growing increasingly longer. Over the course of the week we gain nearly 20 minutes of darkness over daylight! This is a great opportunity to get out to enjoy the last of summer’s stars and the transition to the more sedate skies of fall. An excellent way to do this is to attend the 29th annual "Star Gaze" hosted by the Northern Virginia Astronomy Club on October 1st from 3:00 to 11:00 pm at C.M. Crockett Park in Midland, Virginia. Daytime events will include safe solar observing, games for the kids, and talks by club members and special guests. Once the Sun goes down the wraps will come off club members’ telescopes, and targets such as the Moon, Jupiter, Comet Garradd and the supernova in Messier 101 will be fair game as the night progresses. The program is free, but a nominal parking fee is charged by the park authorities. If you’ve ever had an interest in amateur astronomy, this is a great way to get introduced to the hobby.

The nights of early autumn are my favorites for enjoyable stargazing. The early parts of the evening offer most of the delights of the summer sky without the haze and humidity that so often bogs down July and August nights. The cooler air also tends to keep the mosquitoes at bay but is still pleasant enough to enjoy without losing feeling in your extremities. It gets fully dark shortly after 8:00 pm when the brighter star clouds of the Milky Way split the sky from the southwest to the northeast. The ghostly glow of these clouds yields to modest optical aid, transforming into vast swarms of faint stars and glowing patches of bright star clusters and gaseous nebulae in a steadily held pair of binoculars. A good low-power spotting scope will bring out more detail in these features, and each increase in telescope aperture reveals denser layers of faint background stars. Sweeping along the Milky Way is one of my favorite fall pastimes, whether I’m using my 3-inch "rich field" telescope or my 14.5-inch reflector. The grandeur of our home galaxy is apparent in either instrument. As the night passes and the Milky Way settles toward the west the more sparse stars of late autumn take over center stage in the sky. This is where the larger telescope comes into its own, probing between the stars for distant fuzzy flecks of light shed by distant galaxies, but even here there are treats for much smaller instruments. The Andromeda Galaxy, which can be found easily by looking northeastward from the upper-left "corner" star of the Great Square of Pegasus, is an easy binocular target, and the famous "Double Cluster", which lies in the Milky Way between Cassiopeia and Perseus, is best seen in smaller telescopes whose wider low-power fields of view place it in context with the surrounding star clouds.

As the hours tick by to 11:00 pm or so, the bright glow of Jupiter dominates the eastern sky. Old Jove is coming into his prime for this observing season, and during the late evening hours he offers great views of his four bright Galilean moons and striped surface. Small telescopes should reveal his two prominent equatorial cloud belts, and as you step up in aperture more of his subtle streaks, spots, and bright bands will come into view. On nights of very steady air a good 8-inch telescope will keep you spellbound for hours as you study finer details in Jupiter’s cloud tops. You’ll notice the planet’s rapid rotation in as little as five minutes, and if you take a look an hour later you’ll see completely new features that have spun into view. From our Earthbound perspective Jupiter is the most dynamic world in the solar system.

Pre-dawn skywatchers can watch the ruddy planet Mars pass through the heart of the binocular star cluster known as the Praesepe or the "Beehive". The red planet is halfway up in the eastern sky at 6:00 am among the faint stars of the constellation Cancer. He glides through the star cluster between September 30th and October 2nd.

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