Glossary term: Oort Cloud
Description: The Oort Cloud is a hypothetical region of the outer Solar System that is thought to be the origin of comets with long orbital periods. The Oort Cloud likely contains many billions of small icy bodies left over from the formation of the Solar System. This is thought to form the reservoir for long-period comets. Occasionally one of these frozen lumps will have its orbit disrupted by another icy body, or by the gravity of a star passing the Solar System. This may send the icy body falling towards the inner Solar System where it becomes a comet. The Oort Cloud probably extends from a few thousand astronomical units (AU) to perhaps over a hundred thousand AU, halfway to Proxima Centauri, the nearest star to the Sun. The inner Oort Cloud is likely a donut shape, but the outer Oort Cloud is probably a spherical shell.
Related Terms:
See this term in other languages
Term and definition status: This term and its definition have been approved by a research astronomer and a teacher
The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".
