Solar System Exploration Division
Solar System Tour - Oort Cloud

Oort Cloud

Oort Cloud

The distant Oort cloud marks the gravitational edge of the Solar System, in a vast region of undiscovered objects. The boundary between the Kuiper Belt and Oort cloud is less distinct.

Diagram of the Oort Cloud

The comets that didn't quite escape wound up forming the Oort Cloud, a vast storehouse of comets at the outskirts of the solar system, trillions of miles from the sun (compared to Pluto's average distance of less than 6 billion miles).
Credit: (NASA/JPL)

Short-period comets may originate in the scattered disk, inner, part of the Oort cloud, while long-period comets likely come from the spherical, outer, portion of the Oort cloud. These comets only pass the Sun on rare occasion, possibly when disturbed by distant passing stars or galactic tides. There is speculation of other large planets in this region that may disturb comets in their vicinity, but none have yet been discovered.

Fun Facts

  • the Oort cloud objects may have formed closer to the Sun, but were scattered farther out

  • Some small bodies in the Solar System may have been captured from the Oort cloud