Kirkwood gaps
Kirkwood gaps,
regions in the asteroidasteroid,planetoid,
or minor planet,
small body orbiting the sun. More than 300,000 asteroids have been identified and cataloged; more than a million are believed to exist in the main belt between Mars and Jupiter, with many more in the Kuiper belt
..... Click the link for more information. belt within which few asteroids are found. Astronomer Daniel Kirkwood first observed (1886) that few asteroids had an orbital period close to 1-2, 1-3, or 2-5 that of Jupiter. The gaps could have been formed by collisions between asteroids; however, the most widely accepted theory is that the gaps were formed by gravitational interactions with Jupiter, which over time would move any small body into another orbit.
Kirkwood gaps
(kerk -wûd) Gaps in the distribution of orbits within the main asteroid belt, corresponding to the absence of orbits with periods that are simple fractions (1/4, 1/3, 2/5, 1/2, etc.) of the orbital period of Jupiter (see illustration). Asteroids with such orbital periods would be perturbed into orbits of high eccentricity by the regularly recurring gravitational pull of Jupiter. These asteroids would then cross the orbits of Mars and Earth, with a high chance of colliding with these planets. The US astronomer Daniel Kirkwood first explained these gaps in 1857.