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The Sky This Week, 2014 September 16 - 23

Fuzzy things in the night...
M31_140830_03small.jpg
Messier 31, the Andromeda Galaxy
Imaged 2014 August 30 from near Morratico, Virginia, USA
80mm (3.1-inch) f/6 Antares Sentinel refractor on iOptron Cube Pro mounting,
Canon EOS Rebel T2i DSLR

The Moon greets night owls and early risers this week, waning through her crescent phases to New Moon, which occurs on the 24th at 2:14 am Eastern Daylight Time.  You’ll find her in the wee hours drifting among the rising stars of late winter and early spring.  On the morning of the 17th she passes just a degree north of the second-magnitude star Alhena in the constellation of Gemini.  On the morning of the 20th look for her about five degrees south of bright Jupiter.  On the 21st she is about the same distance south of Regulus in the constellation of Leo.

The autumnal equinox falls on the 22nd at 10:29 pm EDT.  At this time the center of the Sun’s disc will stand directly over Earth’s equator at a point just north of the island of New Guinea, and the astronomical season of autumn will begin in the Northern Hemisphere.  However, because the Sun is not a point source of light, the day when we actually see 12 hours of daylight and 12 hours of night won’t occur until the 26th. From then until March 17, 2015 the length of night will exceed the length of day.  Astronomers, take heart!

With the Moon out of the way for the next week we can take advantage of the clear autumnal air to gaze at the Milky Way, which still runs prominently from the northeast to the southwest during the mid-evening hours.  Even if you can’t see the galaxy’s ghostly glow from your location you can visualize its path by looking at the placement of the brighter stars in the sky.  The Milky Way courses up from the southern horizon between the ruddy star Antares in the constellation Scorpius and the prominent “Teapot” asterism of Sagittarius.  Overhead it pierces the center of the Summer Triangle formed by the stars Vega, Deneb, and Altair.  High in the northeast you’ll see the familiar “W” shape of the constellation Cassiopeia.  This is one of the best areas of the sky to view with binoculars from dark locations as it offers a number of wonderful star clusters for your enjoyment.

By midnight the Summer Triangle shifts to the western sky as another geometric figure approaches the meridian high in the east.  Four second-magnitude stars form the “Great Square” of Pegasus, the mythical flying horse of the Perseus legend.  If you face south, look for two diverging “chains” of stars emanating from the square’s upper left corner star, Alpheratz.  Use binoculars to “hop” to the second star in the lower, brighter chain, then “hop” up past two faint stars.  You should see a fuzzy elongated swath of light which is the signature of our largest near-galactic neighbor, the Andromeda Galaxy, or Messier 31.  From a dark-sky site it is quite easy to find with the naked eye, which makes it the most distant object, at 2.5 million light-years, that can be seen without optical aid!  M31 is about twice the size of our Milky Way and is slowly approaching us in space.  This will result in a spectacular collision in a few billion years, but personally I don’t plan on being around to see it!

Closer to home we still have Mars and Saturn gracing the early evening sky.  You’ll have to act quickly to catch a good glimpse of Saturn as the ringed planet now sets at around 9:30 pm.  Getting a good view of him through the telescope now requires a flat southwestern horizon and a night of very steady air, but you can still see his mysterious rings in small telescopes despite his low altitude.  Ruddy Mars continues to keep pace with the Sun, however, and lingers in the sky until around 10:00 pm.  Mars spends the week closing in on the bright star Antares in Scorpius.  The star’s name means “Rival of Mars”, and you’ll now have a couple of weeks to make that comparison for yourself.

The hours before sunrise offer a good view of giant Jupiter, steadily rising a few minutes earlier each night.  He dominates the eastern sky at around 6:00 am after receiving a visit from the Moon on the 20th.  We’ll start observing him through the telescope soon once he clears the roofline of the house!

Dazzling Venus now rises less than an hour before the Sun, and by the end of the week the margin is down to just 43 minutes.  You can see her bright glow if you have a clear eastern horizon, but she’s only about nine degrees high when Old Sol crests the skyline.

 

 

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