Friday, May 29, 2009

The emptiness of space

In today's excerpt - the emptiness of space, the distances between planets and stars:

" 'The universe is a pretty empty place, and that's something most people don't get' said Michael Brown of Caltech. 'You go watch Star Wars, and you see the heroes flying through an asteroid belt, and they're twisting and turning nonstop to avoid colliding with asteroids.'

In reality, he said, when the Galileo spacecraft flew through our solar system's asteroid belt in the early 1990s, NASA spent millions of dollars in a manic effort to steer the ship close enough to one of the rubble rocks to take photos and maybe sample a bit of its dust. 'And when they got lucky and the spacecraft actually passed by two asteroids, it was considered truly amazing,' said Brown. 'For most of Galileo's journey, there was nothing. Nothing to see, nothing to take pretty pictures of. And we're talking about the solar system, which is a fairly dense region of the universe.'

"Don't be fooled by the gorgeous pictures of dazzling pinwheel galaxies with sunnyside bulges in their midsections, either. They, too, are mostly ghostly: the average separation between stars is about 100,000 times greater than the distance between us and the Sun. Yes, our Milky Way has about 300 billion stars to its credit, but those stars are dispersed across a chasmic piece of property 100,000 light-years in diameter. That's roughly 6 trillion miles (the distance light travels in a year) multiplied by 100,000 ... miles wide. Even using the shrunken scale of a citrus sun lying just twenty feet away from our sand-grain Earth, crossing the galaxy would require a trip of more than 24 million miles."

Natalie Angier, The Canon, Houghton Mifflin, Copyright 2007 by Natalie Angier

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