Oort Cloud
The Oort Cloud is a distant, roughly spherical shell of icy objects believed to surround the Solar System and supply long-period comets.
How big is it?
3.163 ly across
Diameter · approximate
A little perspective
Distance to Proxima Centauri is about 1.34 times larger on this measurement.
Distance to Proxima Centauri: This is the distance from the Sun to Proxima Centauri, the closest known star to our Solar System.
Measurements, assumptions & sources +
Oort Cloud
A conceptual 200,000 AU diameter corresponding to a 100,000 AU outer radius. This distant comet reservoir is inferred, with a very uncertain extent. The illustration is a boundary diagram; dots identify objects or regions and do not depict their physical diameters.
The marked diameter is calibrated. Unmeasured illustration details are representative.
Distance to Proxima Centauri
Rounded NASA nearby-star distance anchor, 4.25 light-years. The Earth is not at the centre of the galaxy.
NASA — Our nearest celestial neighbour
The marked distance is calibrated. Unmeasured illustration details are representative.
Change your perspective
Put it next to…
Choose a suggestion to redraw the comparison, or open its page to learn what it is.
Why this measurement?
Why we use 3.163 ly
For comparison, this page uses diameter. This is labelled approximate; the central value is useful for comparison, while real values or measurement solutions can vary.
A conceptual 200,000 AU diameter corresponding to a 100,000 AU outer radius. This distant comet reservoir is inferred, with a very uncertain extent. The illustration is a boundary diagram; dots identify objects or regions and do not depict their physical diameters.
The marked horizontal span follows the named feature; transparent margins and unmeasured details do not alter it. How calibrated comparisons work →
Recorded properties
Oort Cloud dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 3.163 ly | Not recorded | approximate |
Around this scale
Go smaller. Go bigger.
These links use compatible length records, ordered around the selected value.
Nearest lower value · SpacePlanetary Solar System60.22 AUThe Solar System is the collection of the Sun and all objects gravitationally bound to it, including planets, moons, and smaller bodies.
Nearest higher value · SpaceDistance to Proxima Centauri4.25 lyThis is the distance from the Sun to Proxima Centauri, the closest known star to our Solar System.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- NASA — Oort Cloud factsThe inferred cloud extends as far as about 100,000 AU from the Sun; it is not a directly mapped hard shell.
More ways to see it
Curated comparisons
There’s always another scale
Follow your curiosity.
SpaceEarth–Sun distance1 AUThe Earth–Sun distance, or astronomical unit, is the standard measure of separation between Earth and the Sun used in astronomy.
SpaceMilky Way30.66 kpcThe Milky Way is a spiral galaxy containing hundreds of billions of stars, including our Solar System.
SpaceObservable universe28.21 GpcThe observable universe is the region from which light or other signals have had time to reach us since the early universe.SpaceDistance to Proxima Centauri4.25 lyThis is the distance from the Sun to Proxima Centauri, the closest known star to our Solar System.SpaceDistance to Sirius8.6 lyThis is the distance from the Sun to Sirius, the brightest star in the night sky.SpaceNeptune’s orbital distance30.11 AUNeptune’s orbital distance is the average separation between Neptune and the Sun.SpaceDistance to the galactic centre7.972 kpcThis is the distance from the Solar System to the centre of the Milky Way galaxy.SpacePlanetary Solar System60.22 AUThe Solar System is the collection of the Sun and all objects gravitationally bound to it, including planets, moons, and smaller bodies.