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The Sky This Week, 2016 February 2 - 9

Of shadows and dark skies
The "Horsehead Nebula" and surroundings in Orion
Imaged from near Morattico, VA, 2016 January 3
80 mm (3.1-inch) f/6 refractor and Canon EOS Rebel T2i DSLR

The Moon graces the pre-dawn sky as a waning crescent this week, passing through the rising stars of early summer in the southeast. New Moon occurs on the 8th at 9:39 am Eastern Daylight Time. Look for Luna about four degrees northwest of yellow-hued Saturn on the morning of the 3rd. On the morning of the 6th she forms a compact triangle with the dazzling planet Venus and the more subdued glow of elusive Mercury. This will be a rare opportunity to glimpse all five of the "naked-eye" planets as well as the Moon in the sky at the same time!

According to folklore, the lack of a shadow cast by an indigenous rodent in rural Pennsylvania this morning is an indicator of an early spring. As we mentioned last week this observance has ancient roots tied to the mid-point of the astronomical season of winter. The actual "cross-quarter day" as measured by the astronomical calendar falls on the 4th, just over six weeks from the vernal equinox. Meteorological spring begins on March 1st, so whether the groundhog sees his shadow or not the end of winter is inevitable. If nothing else, this quaint tradition only serves to remind us of how important the motions of the sky were in human culture. Watching the Sun, Moon, planets, and stars was an integral part of our ability to sense and manipulate the passage of time and to use that skill as a tool for planning our future activities. This trait distinguishes us from all other species on the planet and has led us to the most distant frontiers of exploration of the space around us.

Your view of that space around us is probably hampered by our ability to turn night into virtual day thanks to artificial night lighting. You can help to quantify how much of the night sky we’re losing by participating in the Globe at Night citizen-science program between now and the 10th. The program invites observers from around the world to observe and count the number of stars they can see in the prominent winter constellation of Orion, the Hunter. Orion is very well-placed for viewing between 8:00 and 10:00 pm EST, high in the southern sky. You can use the Globe at Night’s web app to make your reports or use one of the apps available for smart phones. There’s even an app for recent-model iPhones that use the device’s camera to measure the brightness of the sky and report it directly to the observation database. You are encouraged to make multiple observations, especially if you can observe from many different locations. The objective of this research is to raise global awareness about the spread of light pollution and its effects on the global ecology. Unlike many more complicated threats to the climate, this one is relatively easy to fix. Just turn off the lights!

As Orion crosses the meridian, the bright planet Jupiter crests the eastern horizon. By the end of the week the giant planet rises at around 8:00 pm. In just over one month he’ll reach opposition, so we’re now in the middle of "prime-time" observing of the distant world. He’s well up by midnight and presents a disc that’s easily resolved in small telescopes. Larger instruments will show a wealth of detail on his alternating bright and dark cloud formations, and a four inch telescope should be sufficient to show his famous Great Red Spot. This feature is particularly well-placed on the night of the 7th, when it lies on the planet’s centerline just before midnight.

Mars is still best placed for viewing before sunrise, crossing the meridian at around 6:00 am. The red planet is beginning to brighten as Earth approaches him on or faster, inner orbit around the Sun. Small telescopes will reveal a small bright pink-hued disk, while modest instruments of five or six inches should start to show some surface detail.

Saturn receives a visit from the Moon before dawn on the 3rd. The duo form a wide triangle with the ruddy star Antares in the constellation of Scorpius. Saturn’s rings are tipped generously toward our line of sight, so they can be seen with virtually any optical aid.

Venus and Mercury are separated by around five degrees all week, with Mercury reaching his greatest elongation from the Sun on the morning of the 7th. If you can find Venus in the brightening morning twilight, use binoculars to look for Mercury between Venus and the horizon. On the morning of the 6th the two planets are visited by a slender waning crescent Moon. You should be able to find all three objects in a tight triangle about 10 degrees above the southeast horizon.

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