Oort Cloud

Region · Hypothesised comet reservoir · orbits Sun

Far beyond the planets, the Solar System is thought to be wrapped in an immense spherical shell of icy bodies - the Oort Cloud. It marks the true edge of the Sun’s domain, its outer reaches extending perhaps halfway to the nearest star, and it is where the great long-period comets like Hale-Bopp come from.

Open the 3D Solar System

Quick facts

A sphere, not a disc

Everything from the planets to the Kuiper Belt orbits in a flattened disc, yet long-period comets like Hale-Bopp arrive from every direction in the sky. That is the giveaway: their source must be a spherical cloud - icy bodies scattered outward by the giant planets long ago, then puffed into a shell by the tugs of passing stars and the tide of the galaxy itself.

Physical characteristics

Diameter0 km
Dimensions~2,000 – 100,000 AU (hypothesised) km

Atmosphere and composition

CompositionBelieved to be billions of icy bodies - dirty snowballs of frozen water, methane and ammonia.

What is still uncertain

The Oort cloud has never been observed directly; its existence is inferred from long-period comet orbits. The in-app rendering is a conceptual model visualization, not observational data.

Related objects

Sources