Success!

We now interrupt this blog to report the successful return of Stardust. Back from a seven-year mission, Stardust is a capsule carrying cometary dust from Wild 2, an ineptly-named comet. Samples were taken from the comet's tail back in 2004, and analyzing the particles will shed new light on the formation of the early solar system. I suppose now is as good a time as any to explain what comets are and where they come from.

Out in the far reaches of the solar system there is a vast region of billions of chunks of ice ranging in size from pebbles to mountains. This region is known as the Oort Cloud, named after the Dutch astronomer, Jan Oort, who first proposed the existence of these icy objects 50,000 A.U.'s away from the Sun. (An A.U. is an astonomical unit; 1 A.U. = 93,000,000 miles or the distance from the Earth to the Sun). Because the rocks are so small and so far away, we cannot see them, but their existence can be inferred from the orbits of the comets that pass through our solar system every once in a while. As the comets get pulled out of the Oort Cloud due to random collisions or the gravitational tug of other stars, they get pulled in toward the gas giants and eventually toward our Sun. As the coma or body of the comet heats up, the ice melts and the comet acquires a tail of glowing (ionized) dust particles. Tails can stretch to distances up to 1,000,000 miles long! A beautiful sight indeed.

Galileo Sees the Light, Again

The Milky Way was a mystery in Galileo's time. Greek mythology proposed that the band of clouds in the night sky was a remnant of Hera's breast milk strewn in an arc above the northern horizon (hence the "Milky" Way). When Galileo looked at our galaxy with his telescope he could easily see points of light that could only be too far away to have a parallax shift. Why would God create objects that humans couldn't resolve with their own eyes? Once again he was baffled by what he saw, and yet he saw the light.