Athena's Web Weekly Column

  Week of September 9th - September 15th,  2011


Columns Archive


M-101 again

Dipper and Bear
The triangle at the tip of the tail

  The heavens have jumped to life and call to us now. Here's the report straight from ABC:

  Twenty-one million light years away- right next door when you consider the size of the universe- something unspeakably violent has happened. A star has died, exploding into what astronomers call a supernova.


M-101, the Pinwheel Galaxy

  That's the bad news. The good news is that it's sufficiently far away that we earthlings can see it through a telescope, if you know where to look and have a bit of patience.

  It was first spotted Aug. 24, is expected to reach its maximum brightness Thursday or Friday night- though, on the scale astronomers use, it will have a magnitude of 10, which is far too dim for the naked eye. But it's bright enough that amateur astronomers will be able to find it with a three- or four-inch telescope.

  Conveniently, it's right near the Big Dipper, that constellation most of us learn to pick out in the northern sky when we're little kids. Just north of Alcor, the star that marks the bend in the "handle" of the dipper, there is a dim dot- a galaxy known as the Pinwheel Galaxy.

  The supernova is in the galaxy- the bright star in the picture above, at about 5 o'clock relative to the center of the galaxy. This picture was taken a few nights ago, and since then it has become brighter than the center of the pinwheel.

Sky and Telescope cover April 2011

Alan McRobert

  "This is the brightest supernova that's been visible from the latitudes of North America in decades" said Alan MacRobert, a senior editor of Sky & Telescope magazine, in an email this afternoon.

  "And it's a Type Ia, which means it's being studied to death right now because Type Ia supernovae serve as excellent distance markers for things much farther away all across the universe. Here's a chance for researchers to learn more about how they actually work, because this one's big and bright right in our cosmic backyard, relatively speaking."

  It's easy to spot where the supernova is, but you'll need some magnification to actually see it. This sort of thing doesn't happen every weekend and you should check it out if you have a chance.

Sky and Telescope cover April 2011

April 2011

  The seven stars of the Big Dipper (the brightest stars of Ursa Major) are among the most universally known. Unlike the stars of Orion, Leo, Scorpio and the Twins which are all seasonal (they come and they go), the Big Dipper is up all year long, no matter what the season, claiming the celestial highground.

  The first two stars in the handle of the Dipper are Benetnash and Mizar, eta and zeta Ursa Major. Eta is the tip of the tail, logging in at about 27 degrees Virgo, whille zeta is a little short of 16 Virgo, the next star in the tail. The supernova in the pinwheel galaxy (M-101) falls between the two but is a little higher north, at about 24 Virgo. Taken together, these three form a loose equilateral triangle with each other.

  The pulse is tonight, when the astronomers tell us the supernova will be at its brightest. Let us watch and see. Is the 24th degree of Virgo being stirred in your chart? What is it that the heavenly script is calling our attention to?

  As we discussed this, Lisa was rather impressed when I told her that I could name each of the 110 Messier objects, in order.

  "Really?" she said, her eyes widening.

   "Sure. It's easy. First there's M-1, then M-2, M-3, and M-4..."



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