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The Sky This Week, 2020 February 4 - 11

Fading Betelgeuse, rising bear.
The Big Dipper rising over the Northern Neck, 2019 February 16, Mollusk, Virginia
The Big Dipper rising over the Northern Neck, 2019 February 16.
Imaged with a Canon EOS Rebel T2i DSLR and Omegon mechanical star tracker.
from Mollusk, Virginia.

The Moon waxes to her full phase this week, brightening the winter’s night sky as she passes high over the Great Winter Circle before moving into the rising stars of spring.  Full Moon occurs on the 9th at 2:33 am Eastern Standard Time.  February’s Full Moon is popularly called the Snow Moon, but she has a tough time living up to that name this year.  On the evening of the 5th and morning of the 6th, Luna occults two bright stars in the constellation of Gemini, the Twins.  Here in Washington the 3rd-magnitude star Propus disappears behind the Moon’s dark limb at 7:44 pm EST on the 5th, emerging from the bright limb at 8:35 pm.  At 12:45 am on the 6th the second-magnitude star Tejat goes behind the Moon near Luna’s southern cusp.  The star emerges at 1:09 am.  Observers along the southern limit of the occultation will have a chance to watch a spectacular “graze” as the star disappears and emerges from behind mountain peaks on the Moon’s rugged Limb.  In the Washington area the graze path runs from New Market, Virginia through Fredericksburg and across the Northern Neck.

The nearly-full Moon washes out most of the fainter stars in the sky, but the bright constellations of winter still give us familiar star patterns to enjoy.  By 8:30 pm the distinctive outline of Orion, the Hunter crosses the meridian.  Orion is one of the most recognized constellations in the heavens, visible from virtually all of the inhabited parts of our planet.  This year, however, the Hunter looks a little different than he has in decades.  Orion normally sports two bright first-magnitude stars, Betelgeuse and Rigel, which mark one of his shoulders and knees, respectively.  Normally the stars are fairly close in brightness, but for the past several months Betelgeuse has faded by over one full magnitude.  My most recent view of the star from the past weekend places it at a similar brightness to Alnitak and Alnilam, the left and center stars in Orion’s “belt”.  Betelgeuse has been known to vary in brightness for many years, but the current fading is unprecedented in the historical record.  How long it will continue to fade and how faint it will get is still anybody’s guess, as are the reasons behind the fading.  Betelgeuse is a very old, evolved star, so we may be witnessing the beginning of its ultimate demise into an intense supernova explosion, which could happen this week or 100,000 years from now.  For those of us who think of the stars as “immutable”, this is a fine example that demonstrates the idea of the Universe as a vast evolving system.

The stars of the Great Winter Circle cross the meridian as the evening hours pass.  Looking to the east and northeast we find some of the signature constellations of spring making their way into the sky.  Leo, the Lion, led by its first-magnitude star Regulus, is fully above the eastern horizon by 9:30 pm.  The Full Moon will pass close to Regulus on the evening of the 9th, then move below the Lion’s tail on the following night.  Leo consists of two prominent asterisms.  The first is known as the “Sickle” and consist of Regulus and a semi-circle of second- and third-magnitude stars that sit north of the bright star.  The second asterism lies east of the Sickle and consists of a compact right triangle.  

Looking to the northeast you should be able to easily spot the seven stars that make up the “Big Dipper” asterism, part of the larger constellation of Ursa Major, the Great Bear.  The Dipper is a striking sight at this time of the year, seemingly standing on its “handle”, balancing the “bowl” above.  

Venus remains as the most prominent planet in the evening sky.  She continues to gradually climb northward along the ecliptic in the western sky, while at the same time moving farther from the Sun.  You have plenty of time to enjoy her brilliant glow since she doesn’t set until around 9:00 pm local time.

Early risers should be on the lookout for more planets in the pre-dawn sky.  Mars shines from the area of the sky between the constellations of Scorpius and Sagittarius, now cresting the southeast horizon as morning twilight gathers.  If you have a clear view of the southeast horizon, scan about 10 degrees above the skyline for the bright glow of Jupiter.  The giant planet should be easy to spot by 6:00 am, and you should see a nice contrast between the whitish hue of Old Jove and the pink hue of Mars about 20 degrees to the west.