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The Sombrero

July 2, 2012

Two bright planets are passing through the constellation Virgo this summer. Orange Mars is in the west-southwest at nightfall, with golden Saturn well to its upper left, near Spica, Virgo’s brightest star.

Virgo is best known not for its stars, but for its galaxies. The Virgo cluster, which contains thousands of galaxies, spans much of the constellation. The most photogenic of them all is M104, the Sombrero galaxy.

Through a small telescope, it looks like a tall “crown” of stars surrounded by a broad, thin disk. A dark lane of dust in the disk makes it look like the brim of a sombrero.

American astronomer Vesto Slipher made an important discovery about the galaxy 100 years ago. Working at Lowell Observatory in Arizona, he was studying many of the “nebulae” that sprinkle the universe. At the time, most astronomers thought they were motes of matter inside the Milky Way galaxy, which was thought to be the full extent of the universe.

Slipher found that many of these objects were moving away from Earth at high speed — so fast that there’s no way they could have been contained inside the Milky Way. The Sombrero was the fastest of all. The finding suggested that the nebulae were really separate galaxies of stars far outside the Milky Way. But it took a couple of more decades for most astronomers to accept that finding.

The Sombrero, by the way, is about 32 million light-years away. We’ll have more about the Sombrero tomorrow.


Script by Damond Benningfield, Copyright 2012


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