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The Sky This Week, 2016 January 19 - 26

See all the bright planets at the same time.
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Jupiter, 2016 January 6, 11:54 UT

The Moon brightens the chilly overnight hours this week. Full Moon occurs on the 23rd at 8:46 pm Eastern Standard Time. Luna occults the bright star Aldebaran on the evening of the 19th, then passes through the heart of the Great Winter Circle over the course of the next several nights. January’s Full Moon is popularly known as the Moon after Yule, the Old Moon, or the Wolf Moon. Besides her close brush with Aldebaran, the Moon passes close to the second-magnitude star Alhena in the night of the 21st and just south of the bright star Regulus on the 25th.

The bright Moon once again washes out the sky as she courses along the northern reaches of the ecliptic. Her pale light is accentuated by snow on the ground, making mid-winter nights seem less long and dreary. However, the cold crisp air provides some of the most transparent skies of the year, so bright stars stand out despite the Moon’s light. The stars of the Great Winter Circle surround the central figure of Orion, easily identified by his three bright "belt" stars. In the Greco-Roman sky lore from which our modern constellations are derived, Orion was a son of Neptune who boasted dominance over all the animals of the Earth. A great hunter, he fell in love with Diana, goddess of the hunt. In one variation of his tale he was accidently slain by one of Diana’s arrows, in another he was killed by the sting of a scorpion sent by Juno to break up the romance. The latter is reflected in the sky, with the scorpion placed as one of the summer constellations, opposite Orion so they’d never be in the heavens at the same time. Interestingly, both constellations have bright red supergiant stars as their brightest luminaries. Virtually every civilization that has left us records has depicted Orion as a great hero, warrior, king, or demi-god. Some of the oldest depictions of the constellation link him to Osiris, the ancient Egyptian god of the afterlife and one of the most important deities in their pantheon.

As Orion heels over to the west in the morning hours, the bright planets visible to the naked eye begin to enter the sky one-by-one. The first up is giant Jupiter, currently rising in the east at around 9:30 pm. Old Jove is currently stationed under the eastern "hindquarters" of Leo, the Lion. Jupiter is best known for the four bright moons that were first described by Galileo in January, 1610. Their discovery all but sealed the validity of the sun-centered solar system theory of Copernicus. You can see them quite easily in a spotting scope or a steadily-held pair of binoculars, but the view of the planet itself is also one of the most interesting in the sky. A three-inch telescope will show the planet’s dark equatorial cloud belts, and each increase in aperture brings out finer structure and detail. You’re looking at the top of a vast turbulent atmosphere teeming with unbelievable violence that is in constant turmoil. The planet’s rapid rotation brings new features into view over the course of an hour, and after a complete rotation those features will have changed dramatically.

The next planet to rise is Mars, who comes up at around 1:30 am in the southeastern sky. The red planet is drifting toward the star Zubenelgenubi in the dim constellation of Libra, the scales. His small ruddy disc is still quite small, so seeing any detail will require a large telescope and very steady skies.

Saturn rises just after 4:00 am and will be best viewed as morning twilight begins to brighten the eastern horizon. The planet’s rings are tipped widely toward our line of sight and should be visible with virtually any kind of optical aid, but his low altitude in the southeast will hamper sharp views through larger instruments.

Dazzling Venus rises at around 5:30 am, and should be easily visible throughout the brightening hours of twilight. She will be joined at the end of the week by the fainter glow of Mercury, who is putting in a brief appearance just before sunrise. This week and next will thus be a good time to view all of the naked-eye planets at the same time. You’ll just have to be up before the Sun to do it!

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