The Sky This Week, 2017 February 7 - 14
|The Moon, imaged 2017 February 3 with the USNO's 12-inch refractor
and a Canon EOS Rebel T2i DSLR
The Moon brightens the overnight hours this week, with the Full Moon occurring on the 10th at 7:33 pm Eastern Standard Time. February’s Full Moon is popularly known as the Snow Moon or Hunger Moon, although we’d have a hard time living up to the first name judging by the winter we’ve had so far. There will be a penumbral lunar eclipse coinciding with the Full Moon. Luna enters the penumbral shadow as she rises over the DC metro area, and at maximum eclipse at 7:43 pm you will probably notice a dark grey shading to the Moon’s northern limb. Luna leaves the penumbra at 9:55 pm.
The bright stars of the Great Winter Circle share the limelight with the Moon. The circle is dominated by the familiar figure of Orion, the Hunter, which crosses the meridian at around 8:30 pm EST. Orion is one of the most recognized star patterns in the sky, being visible from every inhabited part of the planet. We can trace the origins of Orion back to the ancient Egyptians, who early in their civilized history linked the constellation to Osiris, their great god of the underworld. The Pharaoh himself was transformed into Osiris upon his death, and texts pertaining to this transformation can be found in the texts inscribed on the walls of pyramids from the Fifth Dynasty. References to Orion can be found in such diverse religions as Hinduism and Christianity, where the Hunter is mentioned in the Bible’s Book of Job. Even the inhabitants of J.R.R. Tolkien’s Middle Earth had a name for the constellation, calling him "Menelvagor", the Swordsman of the Sky. The constellation’s most notable feature is the "belt" of three stars that run diagonally between the bright reddish star Betelgeuse and icy-blue Rigel. These three stars would be ranked among the brightest in other constellations, but here they play second fiddle to the first-magnitude luminaries. Each of the Belt Stars is a very hot "blue supergiant" star located at vast distances from the Earth. The middle star, Alnilam, beams at us from over 2000 light-years away. If it were located at the same distance as nearby Sirius (a mere 8.6 light years distant) it would shine in our sky with the equivalent brightness of the first-quarter Moon! Most of Orion’s stars are similar in nature, having formed in the heart of a vast cloud of hydrogen gas and dust that pervades long-exposure images of the constellation.
The dazzling planet Venus is now at her best showing for the evening sky this year. Glowing with a staggering -4.8 magnitude, she is at her highest and brightest now and for the next couple of weeks. From a dark location her glow is bright enough to cast shadows on a moonless evening stroll. Her sparkle is readily seen in broad daylight if you know just where to look for her, looking like a sun-glint from a high-flying airplane. On nights with moderate overcast her glow and that of the Moon are the only objects that cut through the murk.
Mars appears just east of Venus and continues to slide eastward against the faint stars of Pisces. His steady pace begins to leave Venus behind as the latter begins to slow her motion before falling back toward the Sun.
Late-night skywatchers will begin to notice the bright glow of Jupiter in the east if they are out at midnight. The giant planet rises at around 10:30 pm EST, but he doesn’t cross the meridian until 4:00 am. Your best view of him will still be during the hours before sunrise.
Saturn rises at around 3:30 am and is visible low in the southeast as morning twilight begins to gather. The ringed planet will spend most of this year’s apparition at his lowest declination during his 29.5 year circuit of the sky. This doesn’t bode well for Northern Hemisphere observers, and we’ll have to be content to view him through the turbulence of our atmosphere as he heads toward opposition shortly before the summer solstice.