The Infinite Possibilities in a Tiny Smudge From Outer Space
If alien astronomers observed our solar system from a distance 4.5 billion years ago, they would have seen a star surrounded by primordial gas and dust. That material, arranged in a narrow but dense disk, whirled round and round the young star. Over time, its particles collided and formed clumps. Gravity smoothed the jagged edges of the biggest ones to make planets and moons, and left the bits and pieces to become asteroids and comets.
The same process happens around other stars across the universe. with the help of powerful telescopes. It doesn’t look like much, but that small, flying-saucer-looking thing in the image at the top of this article is a planetary system in the making. The little bright bulb in the darkness, encircled in its own ring of dust and gas, is known to astronomers as a protoplanetary disk. This is what our cosmic home looked like in the beginning, long before its star became known, to a bunch of life-forms on the third planet from the center, as the sun.
