Betelgeuse - Orion's Red Shoulder

I love the constellation of Orion, it was the first constellation I learned to recognise in the night sky.  I've been ill for a few weeks so I've not been able to get out with the telescope, so I've been doing some reading about Betelgeuse, Orion's red shoulder.

Betelgeuse is a red supergiant, and it's the 10th brightest star in the sky. It's colour is actually visible to the naked eye - next time you look, try comparing the colours between Betelgeuse and Rigel on Orion's knee. It's actually an unstable star, and it fluctuates between 300 and 400 times the size of the sun, and so it's apparent magnitude changes from 0.4 to 1.2.

It's cooler than our Sun, scientists think the temperature is 3300 degrees Kelvin whereas our Sun is 5778 degrees Kelvin.  It's actually 1000 times more massive though, and its size is huge - if it was placed in our Solar System, it would reach out almost to Jupiter's orbit.  Wow! Lucky it's 640 light years away, huh?

Scientists say that though the star is young, it has probably already fused it's Hydrogen and has begun to fuse Helium.  It will eventually work through its other elements - neon, magnesium, sodium and silicon down to its iron core before it collapses into a type II supernova.  That will definately be a sight to see! 

Finally, it's the only star other than our own that NASA has got a surface image of, the first was in 1995, by Hubble:







image credit NASA, for more info on the image, click here