Key facts
- Category
- Planetary systems
- Object class
- Comet reservoir
- Composition
- Icy planetesimals and comet nuclei
Oort Cloud
3.17 lyextent
Visual creditscaleofspace.org / CC BY-NC 4.0
Details
The Oort Cloud is the vast, probably spherical reservoir of icy bodies thought to surround the Sun far beyond the planets. Long-period comets from this region can take thousands or even millions of years to complete one orbit, and Voyager 1 would need about 300 years just to reach its inner edge.
The Oort Cloud has not been directly imaged as a structure. Astronomers infer a distant, roughly spherical reservoir of icy bodies from the orbits of long-period comets and from models of how the forming planets scattered small objects outward.
Its inner and outer boundaries are uncertain, so the 3.2-light-year extent shown here is an approximate model scale. At those distances, passing stars and the Milky Way’s gravitational tide can perturb weakly bound bodies and send some toward the inner Solar System.
Links
- Universe journey
- Oort Cloud
- Wikipedia
- Oort Cloud on Wikipedia
Size neighbors
Objects near Oort Cloud on the scale
On the logarithmic size axis, Oort Cloud falls between Ring Nebula and Helix Nebula. The band uses nearby Planetary systems records.
Shared physical scale
2.42ly
Sources
References for Oort Cloud
Measurements and descriptive context are compiled by the Scale of Space team from the references below. If you find an error, please let us know.
- Oort Cloud — Wikipedia
- Visual: scaleofspace.org / CC BY-NC 4.0
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Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.
Guides explain selected parts of that range, while focused views filter the objects by subject.