Right now one of the current mainstream origin theories is that "we" (all life on earth) is actually alien, the result of biomaterial deposited by a comet strike.

There are several billion galaxies visible from earth. There are more than 10,000 in the Hubble Ultra Deep Field photograph and that's one tiny little portion of the sky. Each galaxy has hundreds of billions of stars.

The first time I really looked at this picture, I literally couldn't breathe. Seen from the ground, this photo represents an area of the night sky that looks almost empty and is one-tenth the size of the diameter of the full moon. It's like looking "through the end of an 8' soda straw at the night sky."

http://upload.wikimedia.org/wikipedi...deep_field.jpg