Wednesday, August 3, 2011

Island Universe

Or three.

The large object in the image is the Andromeda Galaxy, aka M31, the sister galaxy to our home Milky Way. There are two other galaxies in this image. Almost directly above the center of M31 is M110. At the 4 o'clock position from M31's core is M32 (it looks like a large blurry star). As always, click on the image to bigafy it.

The first known record of the Andromeda galaxy is form the 10th century by the Persian astronomer Abd al-Rahman al-Sufi. al-Sufi described it as a small cloud, an accurate description of the naked eye appearance at a dark site. To me it is a football (American style) shaped cloud. But is wasn't until the early twentieth century that astronomers figured out what these small clouds were. It was Edwin Hubble who identified cepheid variable stars in what was then known as the Great Nebula in Andromeda. Cepheid variables have a relationship between their intrinsic brightness and the period of variation, allowing them to be used as celestial mileposts. And the Great Nebula was found to be much to far away to be part of the Milky Way.

And thus was born the modern universe.

The Andromeda Galaxy is 2.5 million light years away, meaning the light that struck the chip in my camera had been traveling for 2.5 million years.

That's a long time.

And this is the closest spiral galaxy to the Milky Way.

The universe is a big place.

1 comment:

Chesney said...

Wow, this is very cool...LOVE, LOVE, LOVE it!