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The Sky This Week, 2011 November 15 - 22

Autumn's dim stars and bright planets

 Map of Jupiter, based on images made 2011 NOV 2 - 12

The Moon courses through the rising winter constellations as the week opens, then moves into the springtime sky before dawn as it ends. Last Quarter occurs on the 18th at 10:09 am Eastern Standard Time. Look for Luna south of the bright star Regulus on the mornings of the 18th and 19th. On the latter morning she will be due south of ruddy Mars. She rises just over three degrees west of blue-hued Spica before dawn on the 22nd.  Luna's glow will put a damper on the  Leonid meteor shower, which peaks on the morning of the 17th.

As the Moon slips into the morning sky the fainter constellation patterns of autumn begin to gradually take form. Many of these star patterns require a trip to dark skies to see with much clarity. Capricornus, Aquarius, Pisces and Cetus occupy much of the southern sky in the early evening hours, and between them they can muster only a handful of 2nd-magnitude stars. Only one first-magnitude star may be found here, on the meridian near the southern horizon at around 7:00 pm. This is the star Fomalhaut in the constellation Piscis Austrinus, the Southern Fish. Fomalhaut lies about 25 light-years from Earth and appears to be moving through space with about 20 other bright stars including Castor and Vega. In 2008 the Hubble Space Telescope made the first visual detection of an extra-solar planet orbiting this isolated entry in our southern sky. The only prominent fall constellations may be found clustered near the zenith on mid-November nights. Andromeda, Cassiopeia, Pegasus and Perseus all share the same mythology and each is composed of relatively bright stars. Cassiopeia and Perseus are splendid targets for binoculars, with many star clusters and associations for your perusal. Andromeda and Pegasus host dozens of distant galaxies, the brightest of which, the Great Andromeda Galaxy, may be seen with the naked eye from dark sky locations.

Evening twilight is now graced by the bright glow of the planet Venus, which is now beginning to climb away from the southwest horizon for darker skies. She is now becoming quite easy to find in the fading light of dusk, setting almost 90 minutes after the Sun. She and elusive Mercury part ways this week. The two innermost planets have been within two degrees of each other for most of the past two weeks, but Mercury makes a turn back toward the Sun and Venus leaves him in her wake.

Giant Jupiter is the planet to keep an eye on during these lengthening nights. He’s visible within minutes of sunset in the eastern sky, and climbs quickly to prominence during the dinner hour. By 9:00 pm he dominates the night with his bright glow as if to beckon you to examine him with whatever optical aid is available. I spend almost every clear night observing him from the front yard, and I can only imagine the surprise and delight that Galileo experienced when he first turned his primitive telescope toward Jupiter 400 year ago. Old Jove’s four bright moons continuously whirl about their enormous master and are easily seen in binoculars. With a telescope of six-inches or more of aperture the moons become tiny discs under steady conditions, and as such lend some sense of scale to the huge world that they orbit. If you happen to catch a view of the feature known as the Great Red Spot in transit across the planet’s face, keep in mind the fact that the area of this one feature is equivalent to the entire surface area of the Earth!

Ruddy Mars now rises at around midnight, and in the pre-dawn hours lies high in the southeast near the bright star Regulus. The red planet is slowly brightening as his apparent disc gradually grows bigger in the eyepieces of our telescopes, but he’s little more than a dot compared to Jupiter. He will come into prominence during the springtime months next year.

Golden Saturn may be seen low in the east as morning twilight begins to gather. He’s just east of the bright blue star Spica, and he will remain near the star during his upcoming opposition in 2012.

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