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The Sky This Week, 2018 February 6 - 13

A good week to count stars for science!
M46-47_150216_01small.jpg
Messier 46 (left), Messier 47 (lower right), and NGC 2423 (upper right)
imaged from Morattico, Virginia with a 8-cm (3-inch) f/6 Antares Sentinel refractor
and a Canon EOS Rebel T2i DSLR on 2015 FEB 16.
Note the small planetary nebula NGC 2438 embedded in M46
and the small cluster NGC 2425 southeast of M47.

The Moon moves through the rising summer constellations this week, drifting along the southern reaches of the ecliptic as she wanes from Last Quarter through her crescent phases.  New Moon occurs on the 15th at 4:05 pm Eastern Standard Time.  She starts the week in the company of Jupiter in the pre-dawn sky, then passes northeast of Mars on the morning of the 9th.  Look for Saturn less than two degrees below the Moon before dawn on the morning of the 11th.

The absence of the Moon means that it’s time to go out and look at the stars unfettered by the glow of a moonlit sky.  This week we’re in the second observing campaign for the citizen-science program “Globe at Night”.  First conducted during the 2009 International Year of Astronomy, Globe at Night has compiled over 100,000 observations by people all around the world to measure the impacts of light pollution on the nighttime sky.  Over 15,000 observations were contributed last year alone, and we hope to exceed that number in 2018.  The premise is simple: find a constellation and match the number of stars that you see with finder charts on the project’s website.  You can also download apps for your smart phone that will lead you to increasingly faint stars to rate the quality of your sky.  For February the constellation of Orion is the focal point.  This means that anybody, whether in the heart of the city or in the darkness of the wilderness, should be able to contribute meaningful data.  You can record your results directly through the phone app or by filling out a form on the program’s website.  Let’s hope for some clear skies, and have some fun “doing science”!

You’ll find Orion well-placed for viewing at prime-time.  The Hunter crosses the meridian between 8:00 and 9:00 pm local time.  From urban locations the bright stars that form his imposing figure are easy to spot, and the color contrast between his brightest stars Betelgeuse and Rigel should be apparent to the naked eye.  Binoculars enhance the view especially highlighting the icy blue hues of Orion’s three “belt” stars.  Look just below the left side of his belt for the small asterism known as “the sword”.  Your binoculars should show the middle star of this group surrounded by a glimmer of fuzzy light.  If you have a small telescope, point it at this object and you’ll begin to see the structure of the Great Orion Nebula.  Even from bright suburban skies it’s amazing how 3-dimensional this cloud of glowing gas appears.  From dark skies with large-aperture telescopes the sight is truly amazing, with swirling clouds of bright and dark material filling the eyepiece view.  Under dark skies explore the areas of the faint swath of the Milky Way just east of Orion.  The faint constellation Monoceros, the Unicorn, occupies this part of the sky.  While its pattern is random at best, it’s a treasure trove for binoculars and small telescopes, with dozens of star clusters embedded in the misty glow of our galaxy.  South of Monoceros is the brilliant glow of Sirius, the brightest star in the sky.  Look just below Sirius for the star cluster Messier 41.  Just over 10 degrees east of Sirius look for the twin star clusters of Messier 46 and 47.  They are embedded in a rich star cloud of the Milky Way and are wonderful sights in binoculars and small low-power telescopes.

The Moon cruises by the morning parade of planets, making for a good excuse to get up before the Sun.  Brightest of these is Jupiter, who nears the meridian as morning twilight begins to brighten the sky.  The Last Quarter Moon hangs with the giant planet on the mornings of the 7th and 8th.  Mars follows Jupiter and can be found passing north of his namesake star Antares during the course of the week.  He gets a visit from the Moon on the 9th.  Rounding out the parade is Saturn.  Use the close proximity of the Moon on the morning of the 11th to find him, just south of Luna’s crescent.

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