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The Sky This Week, 2010 January 19 - 26

Orion's stellar nursery and colors in the night
Mars, 2010 January 14, 03:43 UT
South at top. Note prominent north polar ice cap

The Moon waxes in the evening sky this week, climbing high from the dim starfields of autumn’s constellations into the bright stars of the Great Winter Circle.  First Quarter occurs on the 23rd at 5:53 am Eastern Standard Time.  Luna flanks the Pleiades star cluster on the nights of the 24th and 25th.  On the 26th she may be found just three degrees from Al Nath, the star that marks the tip of the “Northern Horn” of Taurus, the Bull.

Despite the bright glow of the waxing Moon, the week’s sky has plenty of stellar targets to enjoy.  This is the time of year when we northerners see the sky’s most colorful array of stars, from the ruddy tinge of Betelgeuse in Orion to the golden hue of Capella, directly overhead at mid-evening, to the icy blue effervescence of Sirius, the Dog Star, obediently following his club-wielding master.  This is a great time of year to bundle up, relax in a lawn chair, and explore the heavens with a pair of binoculars.  A casual glance at most of the stars in Orion will reveal them to be a brilliant blue, which betrays a clue to their origins.  Many of Orion’s bright stars are blue supergiants, born in a swirling tangle of dust and gas that is still forming stars today.  You can spot this area quite easily with your glasses by looking at the middle “star” in Orion’s “sword”, a small asterism that dangles under the left-most of the famous “belt stars”.  A small telescope will show a tight knot of four stars embedded in a small cloud of glowing gas, while larger instruments in dark locations show delicate filaments of gas not only emitting light from the nebula’s core but reflecting the light of the bright stars forming within.  It is one of the most interesting places in the sky to casually explore, and it can be as rewarding to see from your front yard with basic optical aid as it is with a 14-inch telescope on a Blue Ridge mountaintop.

Time is now rapidly running out for giant Jupiter.  He can still be seen in evening twilight, and you may want to catch a quick glimpse of him before he wallows above the horizon in darkening skies.  He has just over a month before he passes behind the Sun to emerge in the early morning sky by late spring.

Fortunately, in the nick of time, the ruddy face of Mars now climbs quickly in the east to take over for fading Jupiter.  The red planet reaches opposition next week, so we are in the ideal window to observe him now.  This isn’t the best opposition to catch his distant face in the eyepiece, though, as he is almost at his most distant point from the Sun.  His disc is barely 14 arcseconds in diameter, a far cry from the more that 25 arcseconds that he spanned in the 2003 perihihelic opposition.  However, his declination puts him high in our sky, so we have less of planet Earth’s atmosphere to contend with when trying to glean details on his distant surface.  Right now his north polar ice cap is the most prominent feature on his disc, and it may be seen with modest telescopes on most clear nights.
Golden Saturn is also making rapid progress into the evening sky.  By the week’s end the ringed planet rises shortly after 9:30 pm.  When Mars is overhead at the midnight hour, shift your telescope to the eastern sky to catch the planet and his nearly edge-on rings.