Saturday, November 7, 2009

Orion's back

I've always loved the constellation Orion and I can't tell you how happy I was to find it in the sky last night. I remember learning a bit about it in eighth grade when we did an astronomy unit, but I decided to learn more about this figure.

Betelgeuse is a red supergiant that's very bright and very close to the end of its life. According to Wikipedia, when it dies, the supernova will be visible from Earth during the day! In the constellation, this is the star at the top left, or what would be Orion's right shoulder.

I basically knew all that about Betelgeuse, but I certainly didn't know/remember that Rigel, Orion's left foot, is even brighter—it's the sixth brightest star in the night sky (Bet. is 12th). It's a blue supergiant and is also at the end of its life.




I think my favorite fact about Orion is that you can see M42 (the Orion nebula) without the aid of a telescope. If you find Orion's belt, there are a few bright spots that appear to hang down from it; the middle one is M42. When I learned this at age 13 I thought this was so cool—and I've never gotten over that.

Finally, I just learned that the stars that make up Orion have been in this configuration for 1.5 million years and will likely be there for another 1-2 million years more. This makes it one of the longest observable constellations.