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The Sky This Week, 2017 January 24 - 31

Other winter wonders.
Messier 38 and NGC 1907, star clusters in Auriga, imaged 2016 December 31
with a 102mm f/6.6 Explore Scientific AR-102 refractor
and a Canon EOS Rebel T2i DSLR from Mollusk, Virginia

The Moon starts the week as a waning crescent in the pre-dawn sky and ends the week as a waxing crescent in the evening sky. In between we’ll have New Moon, which occurs on the 27th at 7:07 pm Eastern Standard Time. You’ll have a great photo opportunity to catch the Moon, Venus, and Mars together in the early evening sky on the 31st, forming a nice grouping spanning about five degrees of the sky.

You can continue contributing your observations to the Globe at Night program through the evening of the 28th. As we mentioned last week, this is a citizen-science program designed to map the distribution of artificial light in our night sky. The focus for this month is the constellation of Orion, the Hunter, one of the most recognized star patterns in the entire sky.

The winter sky offers other bright constellations in addition to Orion, and there are plenty of interesting things to see in these other star patterns. One of the most prominent is Auriga, the Charioteer, which lies directly overhead in temperate northern latitudes at around 9:30 pm local time. Auriga is led by a beautiful yellow-tinted star, Capella, which is the sixth-brightest star in the sky. Capella is a very close double-binary star system consisting of two bright yellow giant stars and two very faint red dwarf companions. Close by Capella you’ll find a small triangle of stars known as "The Kids". In mythology they were associated with Capella, which represented the she-goat that suckled the infant Zeus. The rest of the constellation resembles a pentagon in shape, and its second-brightest star El Nath also marks the tip of the northern "horn" of Taurus, the Bull. From a dark location you’ll see the faint glow of the winter Milky Way coursing through the middle of Auriga, and you can spend quite a bit of time sweeping the constellation with binoculars or a low-power telescope. Charles Messier identified three bright star clusters in Auriga in the 18th Century from his rooftop observatory in Paris, and these are some of the finest examples of their kind in the entire sky. My favorite views of them are through my 4-inch wide-field refractor telescope, which also reveals many other luminous clumps of unresolved clusters among the Milky Way star clouds.

The early evening sky finds Venus and Mars high in the southwest as evening twilight fades to darkness. Venus has been pursuing the red planet for several weeks, and this week she gets about as close to Mars as she’s going to get. They are separated by just over five degrees for the duration of the week, and they will remain close to each other for the next two weeks. During the second half of February they will begin to separate as mars slogs eastward along the ecliptic and Venus begins her precipitous drop toward the Sun. The two planets will get a close visit from the Moon on the evening of the 31st.

Jupiter is still best seen in the pre-dawn sky, but the giant planet is making inroads into the evening sky. He begins to rise just before midnight after the 19th. You’ll find him just over three degrees north of the bright star Spica as morning twilight begins to brighten the horizon.

Saturn can be found low in the southeast as morning twilight gathers. He is now slowly drifting eastward through the starfields of the summer Milky Way just east of the constellation Sagittarius.

Take a few minutes this week to remember some pioneers in the America space program. Fifty years ago on the 27th Virgil "Gus" Grissom, Edward White, and Roger Chaffee perished in a ground test of the first crewed Apollo mission, and 31 years ago on the 28th the Space Shuttle Challenger exploded 72 seconds after launch with its crew of seven astronauts.


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