Some 3 billion years from now we are going to collide with this galaxy.

This is the famous Andromeda Galaxy, now 2.5 million light years from us but getting closer by the day! Andromeda, a.k.a. Messier 31, is the most distant object readily visible to the naked eye. It now shines high overhead for us in the northern hemisphere.

I asked Siri, my iPad assistant, how many stars are in the Andromeda Galaxy, and she said one trillion. She’s right. Recent estimates put Andromeda’s stellar population at 3 or 4 times that of our own Milky Way Galaxy. It’s also bigger. Measuring from the outermost extremities of the disk gives a diameter of over 200,000 light years, twice the size of our home galaxy.

I took this shot last week. It’s stack of five 15-minute exposures with a new Lunt 80mm refractor. The long exposures bring out the faint halo of stars extending beyond the main bright disk, the part you see in a telescope. You can also see Andromeda’s two close companion galaxies: M32, looking like a fuzzy star below the core; and M110, the elliptical galaxy above the core and connected to the main galaxy by a bridge of faint stars.

– Alan, September 27, 2012 / © 2012 Alan Dyer