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The Sky This Week, 2010 April 6 - 13

Celebrate International Dark-Sky Awareness, then go on a planet patrol
Venus & Mercury Visit the Suburbs
Imaged on 2010 April 1
with a Canon PowerShot S2IS digital camera

The Moon wanes in the pre-dawn sky this week, becoming an ever more slender crescent as she moves from the summer constellations to join the rising stars of autumn.  New Moon occurs on the 14th at 8:29 am Eastern Daylight Time.  On the morning of the 11th look for the Moon about five degrees northeast of bright Jupiter in the gathering morning twilight about half an hour before sunrise.


Turn down outdoor lighting to celebrate the natural night sky from the 6th through the 10th of April.  Founded in 2003 by then high school student Jennifer Barlow, National Dark Sky Week has turned international with endorsements from the International Dark-Sky Association, the American Astronomical Association, Sky & Telescope Magazine, Astronomers Without Borders, and the UNESCO International Year of Astronomy 2009 Dark Skies Awareness Cornerstone Project.  More information on IDSA Week may be found at the IDA website.  


The waning Moon and resultant dark skies offer the chance to see the sky in transition from winter’s bright and colorful beacons to the more subdued constellations of spring.  If you stay up until the wee hours you’ll be greeted by the rising stars of summer, along with the shimmering band of the summertime Milky Way.  When we gaze at spring’s signature constellations of Leo, Ursa Major, Boötes, and Virgo we are looking away from the plane of our home galaxy and into the depths of intergalactic space.  Modest telescopes at dark sites will reveal hundreds of distant smudges of light, each a galaxy like our Milky Way harboring hundreds of billions of stars!  


Venus and Mercury continue their early evening dance.  Fleet Mercury reaches his greatest elongation east of the Sun on the evening of the 8th, just three degrees below and to the right of dazzling Venus.  The two planets continue their “formation flying” through the rest of the week, but Mercury fades rapidly by a full magnitude and begins to lag behind the much brighter Venus.  This is the best evening apparition of Mercury for the year, so try to catch him in the first few evenings of the week.


Ruddy Mars is now gathering speed as he treks eastward through the dim stars of Cancer, The Crab.  If you look at Mars through a pair of binoculars you can watch him slowly close in on the famous “Beehive” star cluster.  From a dark site this object can be seen as a nebulous spot with the unaided eye, and quite frankly it offers more to the casual observer than the red planet does.  Mars’ disc is now just over 8 arcseconds across, and in all but the largest amateur telescopes he’s little more than a tiny pink dot.  However, he’ll be with us throughout the rest of the spring and summer months, so don’t dismiss his warm glow just yet.


Saturn now beckons for your attention in the southeastern sky as darkness falls.  The ringed planet transits at around midnight this week, so he’s well-placed for viewing for most of the night.  His rings are tipped nearly edge-on to out sight line, but this helps to show his fainter inner moons to better advantage.  How many can you spot?


Finally, for a preview of summer and fall skies, the giant planet Jupiter may now be seen in gathering morning twilight.  Old Jove will be best seen during the late summer when many of us will be on vacation.  Plan to pack a small telescope so you can enjoy the solar system’s most influential planet.


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