Poor Man's Space Probes Sun. The sun and its planetary satellites were born out of a cloud of dust and gas about 4.5 billion years ago. That's a verdict reached from analysis of meteorites. The asteroid belt that swirls around the sun between the orbits of Mars and Jupiter was once a constellation of about 70 small planets.
Meteorites say so.
That's because the bulk of the objects that have fallen from space spent most their histories in the deep freeze, essentially sitting out of the game as the solar system's principle planets and moons evolved. Chemically, virtually nothing happened to these meteorites for billions of years as they tumbled through space as asteroids. Some rocks were thrown into erratic trajectories that eventually brought the pieces into collision with Earth. Chemically unchanged since the solar system's prelude, they arrive on Earth as veritable time capsules, bearing evidence about the primitive solar system and carrying a record of their journeys through space. But the Earth, because it's so big, and was able to get so hot.