6/15/09 - edwin hubble

In today's excerpt - Edwin Hubble, the man for whom today's Hubble Space Telescope is named, discovers the universe:

"On an October night in 1923 at the Mount Wilson Observatory north of Los Angeles, the view of the night sky was unparalleled. Down in the valley, Hollywood was booming, but the population of the city was still less than a million and the tide of smog and city lights had not yet crept up the mountain. On its 5,700-foot peak stood the largest telescope in the world, a reflecting telescope with a 100-inch-wide mirror. At the eyepiece that night, guiding the mammoth white tube as it tracked the Andromeda Nebula across the sky, sat a 33-year-old astronomer named Edwin Hubble. He was about to redefine our concept of the universe. ...

"The telescope was the second American thing about this story. It's not just that it was the world's largest and thus the instrument that could see the farthest into what Hubble would later call 'the realm of the nebulae' -- it's that it was paid for not by the government, but by wealthy philanthropists. John D. Hooker, a local businessman, footed the bill for the mirror, which was cast in France from greenish wine-bottle glass and then shipped to Pasadena for grinding and polishing. The rest of the money came from Andrew Carnegie, who through his Carnegie Institution, supported science by supporting 'exceptional' individuals like himself. The brains behind the telescope, George Hale, fit that bill, and so did Hubble whom Hale recruited. ...

"According to the other camp, however, those nebulae were not intrinsically faint and wispy -- they only looked faint because they were very far away. There were other galaxies just like our own floating in a much bigger sea of empty space. 'Island universes', Immanuel Kant had called them when he first proposed the theory in the 18th century. ... Hubble had devoted his doctoral work at Chicago to observing nebulae with a 24-inch reflecting telescope; that's what brought him to the attention of Hale. ...

"On the night of October 5, 1923, Hubble noticed a faint star [in the Andromeda Nebula] he had not seen before. Back in his office in Pasadena though, he found the same star on earlier plates -- it was a regularly pulsing star called a Cepheid variable. Astronomers had studied Cepheids in the Milky Way and discovered that the period of the pulsations was a reliable measure of the star's intrinsic brightness. Comparing that with how bright the star appeared on their photographs, they could calculate how far away it was. Hubble did that right away with his first Cepheid. He found that it, and thus the Andromeda Nebula, were one million light-years away -- a distance five times greater than the largest estimate of the Milky Way's diameter. Clearly Andromeda was not part of the Milky Way. ...

"When Hubble's first results were presented at a scientific meeting at the end of 1924, one astronomer pulled out a slide rule to calculate how much the volume of the universe had just grown: a hundred-fold he said. When Harlow Shapley, the leader of the our-galaxy-is-the-whole-shebang camp, received a letter from Hubble in 1924 announcing the Cepheids in Andromeda and another nebula, he is reported to have said to a colleague, 'Here is the letter that has destroyed my universe.' "


Robert Kunzig


'America's Cosmic Frontiersman'


American History


August 2009


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