Universal Monster Picture

Jul 20, 2015

Bright, hot, supergiant star Deneb lies at top center in this gorgeous skyscape.
Credit NASA

  This is “Looking UP! in southern Colorado,” from the Colorado Springs Astronomical Society. I’m Hal Bidlack, and there are lots of reasons to look up!

Last month we talked about the star Vega, one of three stars that make up the Summer triangle, visible to southern Colorado listeners in the East about an hour after sunset. 

Today let’s talk one of the other two stars in that group, Deneb. In the constellation of Cygnus the Swan, Deneb is the tail feather, as the Swan appears to fly majestically down the white glow of the Milky Way, when viewed away from bright city lights. Deneb is a special star in its own right. While it appears to be only the 20th brightest star in the sky, it is actually incredibly bright, but it’s very far away, relatively speaking.

But were not exactly sure how far away Deneb really is. It’s a very strange star, so strange that there is one entire class of stars named after Deneb, the Alpha Cygni stars, that experience a truly weird phenomenon where different parts of the star expand and contract at the same time. This, in part, makes it very hard to figure out exactly how far away it is. Estimates range from about 1400 ly to 7000 ly.

But we do know that Deneb is very likely the most distant star you can see with your naked eye. It’s at least 200 times the diameter of the sun, and burns 250,000 times brighter. It’s a monster star that will someday explode into a supernova that will briefly be as bright as the full moon.

Like the other star we talked about in the summer triangle, Vega, Deneb is occasionally the North Star, due to the earth wobbling on its axis. Deneb will be the North Star in the year 9800, so make a note if you doing in the celestial navigation that year.

And also like Vega, Deneb has been a fixture in science fiction. A Klingon once called Capt. Kirk a “Denebian slime devil,” though with its massive output of energy and weird expanding and contracting, it’s unlikely any planets around Deneb could support life, slime devils or otherwise.

If you’d like to take a closer look at the Deneb or any of the other wonderful and amazing things in the sky, please visit KRCC.org or CSASTRO.org for a link to information on our monthly meetings and our free public star parties! 

This is Hal Bidlack for the Colorado Springs Astronomical Society, telling you to keep looking up, Southern Colorado!