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The Sky This Week, 2015 November 17 - 24

The Navy on the Moon, and USNO's best-known comet.
Moon_151116_01small.jpg
Lunar Terminator, 2015 November 16, 22:50 - 23:10 UT
Imaged with USNO's 30.5-cm (12-inch) f/15 Clark/Saegmüller refractor
1.6X Antares Barlow Lens, and Canon EOS Rebel T2i DSLR

The Moon brightens the evening sky this week, waxing from a crescent low in the southwest to a robust gibbous by the week’s end. With First Quarter occurring on the 19th at 1:27 am Eastern Standard Time, this is a great week to watch the terminator gradually creep across Luna’s face, revealing a different moonscape each night. This week marks the 46th anniversary of the landing of Apollo 12 on the Moon’s so-called Ocean of Storms for humanity’s second lunar surface exploration. The all-Navy crew of Charles "Pete" Conrad and Alan Bean achieved a pinpoint landing in the Lunar Module "Intrepid" at the site of the robotic Surveyor 3 probe’s touchdown in 1967 while Richard Gordon orbited the Moon 45 times in the Command Module "Yankee Clipper". Conrad and Bean deployed the first nuclear-powered suite of science instruments and walked to the derelict Surveyor, bringing its camera and other pieces back for study along with about 35 kilograms (75 pounds) of rocks and lunar soil. Their landing site, now known as Statio Cognito, will be near the terminator on the evening of the 20th, the anniversary of the departure of "Intrepid" from the surface.

Early risers on the morning of the 18th may see a few fast-moving meteors as Earth encounters the scattered debris of Comet 55P Tempel-Tuttle. The annual Leonid Meteor Shower has been known to produce some of the most spectacular sky shows ever seen, with huge outbursts of activity occurring in 1833, 1866, and 1966. During these "storms" thousands of meteors streaked across the sky each hour. More recent displays between 1999 and 2002 also saw increased activity. I watched the 2001 display from a field in Alexandria, Virginia and gave up counting after seeing well over 400 in a half-hour period. The parent comet of this meteoroid stream orbits the Sun with a 33-year period, so we can expect increased performance each time the comet nears the inner solar system. Comet 55P was co-discovered by Wilhelm Tempel in Germany and Horace P. Tuttle here at the U.S. Naval Observatory, the latter spotting it on January 5, 1866. We now know that the Leonid shower has been seen since at least 902 AD. This year’s display will probably not reach "storm" levels, but an observer at a dark sky site can expect to see around 20 or more fast-moving meteors per hour before the onset of morning twilight. The shower is active from the 15th to the 20th.

The bright stars of the Great Winter Circle are gradually finding their way into the late evening sky. As moonlight washes out the fainter stars of autumn it’s nice to find these bright, colorful beacons illuminating the eastern sky. By 9:00 pm you should see the familiar figure of Orion in the east, seemingly jumping up from the horizon. Orion is a wonderful constellation to study with binoculars, offering bright stars with striking colors that are enjoyable even from urban locations.

The bright planets are grouped in the morning sky right now. If you’re up before the Sun you can see them strung out like pearls in the east as the first wisps of twilight begin to light the horizon. Jupiter is now well up in the sky, nearly 45 degrees high at 5:00 am. Dazzling Venus is hard to miss. Even though she was close to Jupiter a mere three weeks ago, she’s left the giant planet in her wake and is now over 20 degrees from Old Jove. In between you’ll see the more diminutive ruddy glimmer of Mars. The red planet will seem to stay equidistant from his brighter rivals through the end of the year.

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