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The Sky This Week, 2020 February 11 - 18

Mars hides behind the Moon, Betelgeuse bottoms out.
Messier 38, galactic star cluster in Auriga.  The smaller cluster is NGC 1907.
Messier 38, galactic star cluster in Auriga. The smaller cluster is NGC 1907.
Imaged with a Canon EOS Rebel T2i DSLR and Explore Scientific AR102 10.2-cm (4-inch) f/6.5 refractor
on 2016 December 31 from Mollusk, Virginia.

The Moon wanes in the morning sky this week, diving through the springtime constellations to wind up the week among the early stars of summer.  Last Quarter occurs on the 15th at 5:17 pm Eastern Standard Time.  You’ll find the Moon several degrees north of the bright star Spica in the constellation of Virgo on the morning of the 13th.  If you’re up before sunrise on the 16th look for Luna just north of the stars that form the “head” of Scorpius.  On the morning of the 18th there’s a chance to see the Moon occult the planet Mars.  You will need to have a clear sky, a good unobstructed view of the southeast horizon, and a pair of binoculars or a small telescope to watch Mars slip behind the Moon’s bright limb at 7:28 am EST.  Sunrise will be at 6:51 am, so the sky will be fairly bright.  Mars emerges from behind Luna’s dark limb at 9:00 am, but this part of the event will be difficult to see. 

In addition to being Valentine’s Day, the 14th marks the start of the February observing campaign for the Globe at Night citizen-science program.  The featured constellation for this month is Orion, which is perfectly placed in the early evening sky.  The folks at Globe at Night are particularly interested in your input for this campaign as they will be comparing current observations with those made back in 2012.  Since that year many outdoor lights have been converted to LED lamps, and astronomers are very interested in how this is changing the view of the night sky.  Making an observation is very easy.  Locate Orion in the sky, let your eyes adapt to the darkness, then compare your view with star charts located on the program’s website.  Your observations can make a difference in the long-term quality of the night sky.

Speaking of Orion, the star Betelgeuse, which usually rivals Rigel in brightness, continues to fade.  My most recent estimate places it on the same level as the brightest of the constellation’s “belt” stars.  The star has long been known to be variable in its brightness, but its current level is unprecedented in its observational history.  However, the big fade may be nearing an end.  Astronomers have determined that the star is experiencing a coincidence in two long-term variable cycles.  One of these is a well-known period of around 430 days, while the other seems to be about six years in duration.  Both cycles seem to be at their minima at this time, causing the star to appear dimmer than it has been for at least a century.  Both cycles should begin to “rebound” in the near future, and it is quite likely that Betelgeuse will begin to brighten by the beginning of March.  Watch this space!

If you are spending the holiday weekend away from city lights, take some time to locate the wintertime swath of the Milky Way.  While it is nowhere near as prominent as it is in the summer months, the faintly glowing band is still worth taking some time to explore.  Running from Cassiopeia in the northwest through Canis Major in the southeast, the soft glow of the Galaxy is peppered with star clusters that are some of the best celestial treats for binoculars and small telescopes.  One of my favorite regions to explore is contained within the pentagon shape of the constellation Auriga, which passes overhead at around 8:30 pm.  Three prominent clusters lie within the constellation’s outline, appearing as bright fuzzy knots in binoculars and resolving into swarms of dozens to hundreds of stars in small telescopes.  Sweep the Milky Way southeastward through the obscure constellation Monoceros, the Unicorn, which lies just east of Orion, and continue to the blazing star Sirius in Canis Major.  There are dozens of other star clusters and glowing clouds of gas to catch your careful eye.

Dazzling Venus appears high in the southeast as the Sun sets.  If you note where Venus appears in your local sky, try sighting her before sunset.  Once you know what to look for you may even be able to sight her when she crosses the meridian at around 3:00 pm.  If that’s too much of a challenge, go to a dark site and look for your shadow cast by Venus’ brilliant glow.

Look for ruddy Mars near the Moon before dawn on the 18th.  The red planet is drifting eastward above the stars that form the “teapot” asterism in Sagittarius, ending the week above the teapot’s “spout”.  As morning twilight begins to brighten the horizon, look for the bright glow of Jupiter between Mars and the southeast horizon.