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The Sky This Week, 2011 October 18 - 25

A good week to count some stars!
Cylindrical projection map of Jupiter based on images
obtained between 2011 OCT 7 & 10

20-cm (8-inch) f/10 Schmidt-Cassegrain telescope with
2X Barlow lens and DFK21AU04.AS CCD camera

The Moon wanes in the morning sky this week, passing through the constellations of winter and early spring.  New Moon occurs on the 26th at 3:56 pm Eastern Daylight Time.  Look for Luna near ruddy Mars in the pre-dawn skies on the 21st and 22nd.  On the latter morning she will be about six degrees south of the bright star Regulus in the constellation of Leo.

The absence of the Moon and the possibility of crisp, clear fall evenings means that it’s time once again for the autumn edition of the Great World Wide Star Count.  This annual exercise in “citizen science” is intended to not only introduce people to the joys of learning to find their way around the sky, but to also sensitize us to the encroachment of artificial night lighting and its impacts on our environment.  The premise is very simple; go outside on the next clear night, identify the constellation Cygnus (for Northern Hemisphere observers) and count the number of stars you see within the constellation’s boundaries.  If you live in an urban site try doing the count from your back yard, then try it again from out in the country.  A great chance to try this comparison will be on Saturday the 22nd, when members of local astronomy clubs will set up their telescopes for public viewing at Sky Meadows State Park near Paris, Virginia, beginning at dusk.  On a good clear night stars as faint as sixth magnitude are visible from Sky Meadows, and there will be a host of other objects to look at under these skies.  While the program is free, there is a nominal parking fee to gain entrance to the park.

Venus is slowly edging her way into the evening sky during twilight shortly after sunset.  You will find her low in the southwestern sky where she should be an easy target half an hour after the Sun goes down.  She will seen to hover in this general area for the next few weeks, but by mid-November she will begin to make a dramatic climb into the sky.  By the year’s end she will blaze with all her glory in the west against a dark starry background.

Bright Jupiter is rapidly approaching opposition, which will occur on the 28th.  The giant planet becomes prominent in the east as evening twilight fades, and as the night hours pass he rises to dominate the overnight hours.  Watching Jupiter with a small telescope can be an endlessly fascinating pastime.  The four bright moons discovered by Galileo in 1610 form a solar system in miniature, and their motions can become quite apparent when they are close to the planet’s disc or each other.  In the latter case, if they happen to be moving in opposite directions, you’ll notice their motion in a matter of minutes.  Increase the aperture of a telescope to the 6- to 8-inch range and detail in old Jove’s swirling cloud tops will parade before you as the planet spins in his rapid rotation.  If you look at him once every hour you’ll see an almost completely different world of spots, streaks and eddies in his turbulent atmosphere.

These last few weeks before we return to Standard Time afford those of us who are not “morning people” a chance to see some of winter’s constellations as well as those of early spring.  Between the faint stars of Cancer and the distinctive shape of Leo you’ll see a ruddy star-like object drifting toward the bright star Regulus as morning twilight gathers.  This is the planet Mars, whose distinctive hue is about the only feature of note right now.  Compared to Jupiter, Mars’ disc is tiny and holds little reward for telescopic inspection.  He’ll put on a better show as we approach mid-spring next year.

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