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The Sky This Week, 2010 April 20 - 27

A Springtime Full Moon, and the planets start a race.
 Venus, Mercury, and a 36-hour old crescent Moon
Imaged from Alexandria, Virginia, USA on 2010 April 15 with a Canon PowerShot S2IS digital camera, 10s. exposure @f/4, ISO 50, 3.5X optical zoon.

The Moon brightens the evening sky this week, waxing to the full phase by week’s end. Full Moon occurs on the 28th at 8:18 am Eastern Daylight Time. April’s Full Moon is popularly called the Grass Moon or Egg Moon, since by now the grass is growing like mad (at least in my yard!) and birds are beginning to hatch their next generation. Luna takes a dive toward the southern reaches of the Ecliptic as she grows ever fatter with each successive night. Look for Luna some five degrees southwest of ruddy Mars on the evening of the 21st. On the 24th and 25th she can be found in the company of Saturn in the southeastern sky as twilight ends. On the 26th and 27th she flanks the blue-tinted star Spica.

April 20 celebrates "The World Night", another event in the Global Astronomy Month calendar. This is another evening when citizens are encouraged to turn off unnecessary outdoor lights and to share views of the evening sky with friends and neighbors. This event is observed world-wide on April 20 as a means of promoting international sky awareness. April 24 is the first of two "Astronomy Days" that will be observed this year. This coming Saturday the Northern Virginia Astronomy Club will host an event at Sky Meadows State Park near Paris, VA between 3:00 and 11:00 pm, rain or shine. This is a great opportunity to find out about amateur astronomy equipment and techniques. There will be safe solar viewing through specially-filtered telescopes, guest speakers, as well as the beautiful sights of the Blue Ridge Mountains for your enjoyment. There is a nominal park entry fee, but the program itself is free.

The early evening sky now hosts dazzling Venus in the deepening twilight. Her recent encounter with the fleet planet Mercury is now but a fading memory as the smaller planet dashes between the Earth and the Sun on the 28th. Venus, however, continues to inch higher into the sky each night, now setting after the end of evening twilight. She is now setting her sights on Mars and Saturn, and all three planets will clump together by mid-summer.

Mars spends the week rapidly pulling away from his most recent encounter with the Beehive star cluster. I watched the red planet pass just north of the cluster last week through my binoculars, and over the course of the next several evenings he’ll put nearly five degrees of distance between himself and the Beehive. Mars continues to accelerate in his eastward trek against the stars, and in just a few months he’ll overtake and pass Saturn.

Speaking of Saturn, the ringed planet is now ideally placed for viewing as evening twilight ends. He’s high in the southeastern sky at this time, hanging just over ten degrees south of Denebola, the star that marks the tail of Leo, the Lion. Through a small telescope you can now glimpse the shadow of the nearly edge-on rings on the disc of the planet, which seems to slice the distant world in two. Dark skies and steady air will allow you to glimpse up to a half-dozen of the planet’s bevy of icy moons.

Early risers should now have no trouble finding giant Jupiter in the gathering twilight of dawn. Old Jove lies just south of due east as the sky brightens, rising about an hour and a half before the Sun. It’s not quite time to put the telescope on his striped cloud belts yet; that will be more of a treat for the summertime sky.

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