Is it ensure, insure, or assure?
|Kirkwood gaps |
Specific regions in the asteroid belt where few asteroids are found. The Kirkwood gaps are believed to have formed as a consequence of gravitational interactions of asteroids with Jupiter, which resulted in the movement of the asteroids from within this area into another orbit, leaving the area sparsely populated. The Kirkwood gaps are named after the American astronomer Daniel Kirkwood (1814-1895), who first observed them in 1866.