Oort cloud comets

The Oort cloud is a vast spherical shell of icy bodies surrounding the solar system, regarded as the source of long-period comets.

About this subject

The Oort cloud is a vast spherical shell of icy bodies surrounding the solar system at distances up to 100,000 astronomical units from the Sun. It is believed to be the source of long-period comets, those with orbits taking thousands of years. Dutch astronomer Jan Oort proposed its existence in 1950 to explain why long-period comets come from all directions, not just the plane of the solar system. The cloud contains trillions of objects, remnants from the formation of the planets. When gravitational perturbations, perhaps from passing stars or galactic tides, send these objects inward toward the Sun, they become active comets. As they approach the Sun, their icy surfaces sublimate, creating the characteristic coma and tails. Unlike short-period comets from the Kuiper belt, Oort cloud comets can have highly inclined and even retrograde orbits. Famous comets like Hale-Bopp and Hyakutake are believed to have originated in the Oort cloud. Recent studies suggest that the Oort cloud may extend further than previously thought, and its total mass could be several times Earth's mass. Although no spacecraft has visited the Oort cloud, future missions aim to study these pristine remnants of the early solar system.

Frequently Asked Questions

What is the Oort cloud?

It is a spherical cloud of icy objects surrounding the solar system, up to 100,000 AU away, giving rise to long-period comets.

Who discovered the Oort cloud?

Dutch astronomer Jan Oort proposed its existence in 1950 to explain the origin of long-period comets.

Which comets come from the Oort cloud?

Comets like Hale-Bopp and Hyakutake are examples of long-period comets originating from the Oort cloud.