¡SkyCaramba! Weekly astronomy blog for the week ending July 25, 2015
Even after Edwin Hubble proved the Great Andromeda Nebula is really a separate galaxy, his own photographs could show it as little more than a smudge of light.
A century ago, astronomers didn’t make much distinction between the universe and the galaxy we live in. They didn’t understand that ours isn’t the only galaxy. Nor did they understand how big the galaxy and the universe really are. They believed that if people could travel just 30,000 light years, they would leave all the stars that exist behind them.
By the 1920s, a few scientists had speculated that far beyond the stars still lay at least some of the nebulae, those glowing smudges that the best optics of the time still couldn’t bring into focus. A few even wondered if nebulae were giant groups of stars separate from the one we live in. But without proof, most astronomers rejected that view.
In 1923, astronomer Edwin Hubble photographed what appeared to be a new star in the Great Andromeda Nebula. He examined more pictures intending to confirm a nova. However, he found that the star was there before. It just hadn’t ...