The small particles drifting in orbit around the developing Sun were initially no bigger than grains of sand. But over time, the particles clustered together, building up into larger and larger bodies, known as planetesimals. While these objects were still relatively small, the growth process was fairly slow and steady. But once planetesimals reached the size of the island of Manhattan, the solar system became a more chaotic and violent place, with planetesimals repeatedly crashing into each other as they orbited the Sun.
These forceful encounters could shatter planetesimals or compact them into one larger body. In some of the most powerful collisions, the energy from the impact heated the planetesimals so much that certain regions began to melt. Evidence of all these processes can be seen in meteorites.
Keywords: Astrogeology, Astronomy, Astrophysics, Meteorites, Planets--Origin, Solar System--Origin