Asteroid horseshoe orbit, illustration. At upper left, an asteroid is orbiting faster than the Earth, with orbits shown as red ellipses. At upper right, the path of the asteroid away from the Earth is shown as a spiralling motion (yellow line) along its orbital path. The view of this motion as seen from Earth is shown at centre left (yellow loop). Over time, the asteroid will catch up with and approach the Earth from behind (centre right), with the Earth's gravitational pull (blue arrow) boosting the asteroid into a larger (slower) orbit (dotted yellow line). In this larger orbit, the asteroid orbits more slowly than the Earth (lower left) until the Earth catches up with it, boosting it into a smaller (faster) orbit, starting the cycle again. The overall shape of this orbit (lower right) resembles a horseshoe.