The Sky This Week, 2013 January 8 - 15
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Jupiter, with Europa, Io, and Callisto |
The Moon slips from the morning to the evening sky this week, with New Moon occurring on the 11th at 2:44 pm Eastern Standard Time. You should be able to catch your last glimpse of Luna in the pre-dawn sky in the brightening twilight on the 10th. At this time her hairline crescent will be just two degrees north of bright Venus, about five degrees above the southeast horizon at 6:45 am. Look for the first crescent of the evening sky after sunset on the 12th. At 6:00 pm the day-old Moon will be five degrees above the southwest horizon, and observers with binoculars may be able to pick out the feeble glimmer of Mars about eight degrees to the southeast.
There are still a few nights left to participate in the current observing campaign for this year’s "Globe At Night" citizen-science program. This first of five events runs through the evening of the 12th, inviting you to make a simple observation of a familiar constellation to contribute to our knowledge of light- and air-pollution in our atmosphere. Those of us in northern temperate latitudes are encouraged to look at the constellation of Orion and simply compare the number of stars we see with charts published on the program’s website. Last year the campaign recorded nearly 17,000 observations from participants in 92 countries, and comparable numbers are hoped for this year. Should weather or other circumstances prevent you from looking this week, the next campaign begins on the 31st.
Whether you’re observing for science or not, the stars of Orion and his surrounding companions now grace the "prime-time" viewing hours. Even from the bright corner of my yard where I set up my telescope to look at Jupiter the stars of the Great Winter Circle are bright enough to grab my attention each night. Nowhere else in the sky will you find such a rich diversity of star colors, ranging from the ruddy tints of Betelgeuse and Aldebaran to the scintillating ice-blue of Sirius and the golden glow of Capella. By 10:30 pm the meridian neatly bisects this gaggle of stars which sports nine of the 25 brightest luminaries in the sky. Each of these bright stars has a story to tell in their starlight, be it their relative proximity to us (as with Sirius and Procyon), their extreme distances (as with Rigel and most of the other stars in Orion) or their old age, best exhibited in the bloated red supergiant star Betelgeuse. I am always amazed at the information we can glean from the photons from these remote places. Unlike most scientific specimens, we will never be able to touch any of them!
This is perhaps the last week to catch a fleeting glimpse of Mars in the evening sky, and your best chance to spot him will be on the 12th and 13th when he is "bracketed" by the waxing crescent Moon. The red planet now sets at the end of evening twilight, so you’ll need binoculars to pull his ruddy glimmer out of the backlit sky.
Jupiter continues to dominate the evening hours. You’ll see him pop out of the twilight glow shortly after sunset high in the east, and he marches steadily higher and westward as the evening progresses. He’s on the meridian and nearly directly overhead just before 9:30 pm. After the Moon, Jupiter is far and away the most easily observed solar system target for small to medium aperture telescopes. You don’t have to watch him for long to see subtle changes. The planet rotates very fast: a "day" on Jupiter is less than 10 hours long. This rapid rotation brings new features into view over the course of an observing session, and if any of his moons are near his disc their motions will be readily apparent over a few minutes. Old Jove occupies quite a bit of my evenings on nights when the air is steady and clear.
Saturn is gradually working his way toward the evening sky. He rises just before 2:00 am EST right now, but in another month he’ll crest the horizon at midnight. He’s best observed just before dawn for the next few weeks. Saturn is a gas giant planet that’s similar to Jupiter in many ways, but his greater distance from the Sun causes less interesting "weather" in his dense atmosphere. However, Saturn sports his famous rings which have tantalized and charmed both professional and amateur observers since the invention of the telescope. He will succeed Jupiter for my undivided attention by late spring!
You might wish to say farewell to Venus this week if you’re up before the Sun. She is headed toward conjunction with the Sun in March, so each passing morning now brings here ever closer to the encroaching solar glare.
