Our solar system, and other planetary systems, started as a disk of microscopic dust, gas, and ice around the young Sun. The amazing diversity of objects in the solar system today - the planets, moons, asteroids, and comets - was made from this primitive dust.
NASA's Stardust mission returned to Earth with samples of comet Wild 2, a comet that originated outside the orbit of Neptune and was subsequently kicked closer to Earth's orbit in 1974 when Jupiter's gravity altered Wild 2's orbit.