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What's in the sky tonight?
September 5, 2013

-As evening twilight fades, spot Venus low in the west. Look below it (by less than 2°) for much fainter little Spica twinkling away. Binoculars help. Saturn glows 14° to their upper left.

-Twice every year, around the time of the equinoxes, Earth can pass directly between the Sun and NASA's Solar Dynamics Observatory (SDO), producing a series of beautiful eclipses from the point of view of the spacecraft. SDO's autumnal eclipse season began this week, producing a partial blackout of the sun. During the eclipse, which was centered around 0658 UT on Sept. 2nd, Earth covered about half of the sun. Because these eclipses typically last for only minutes each day (maximum=72 minutes), there is still plenty of uninterrupted time for SDO to monitor activity on the sun. The ongoing eclipse season will end on Sept. 25th. Below is a youtube video and a picture of such eclipses.

Astro Picture of the Day:
September 5, 2013

Source:
The Crab Nebula is cataloged as M1, the first on Charles Messier's famous list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, an expanding cloud of debris from the explosion of a massive star. The violent birth of the Crab was witnessed by astronomers in the year 1054. Roughly 10 light-years across today, the nebula is still expanding at a rate of over 1,000 kilometers per second. Want to see the Crab Nebula expand? Compare an image of M1 taken in 1999 at the European Southern Observatory, with this one, taken in 2012 at the Mt. Lemmon Sky Center. Background stars were used to register the two images. The Crab Nebula lies about 6,500 light-years away in the constellation Taurus. The 1999 image is found below. Look closely at the stars to either side of the Crab Nebula on both pictures.

http://www.eso.org/public/images/eso9948f/