From the January 2008 issue

Where do comets come from and why are their orbits so elongated?

Jorge Robles, San Diego
By | Published: January 1, 2008 | Last updated on May 18, 2023

Astronomers think comets originate from two “cold storage” zones that surround the planetary system. The inner part of this comet cloud is a thick disk that begins near Neptune’s orbit and extends beyond Pluto’s orbit to about 50 times Earth’s distance from the Sun.