Oort Cloud
A vast spherical shell of icy bodies surrounding the Solar System, the source of the long-period comets.
Overview
A hypothesised spherical cloud of trillions of icy bodies at the outermost edge of the Sun's gravitational influence — the reservoir from which long-period and Halley-type comets are nudged inward.
Members
9 modelled members.
- Hale–BoppC/1995
The 'Great Comet of 1997', a long-period comet with an exceptionally large, active nucleus that remained visible to the naked eye for a record 18 months.
TypeLong-period cometDiscovered1995Great cometYes - Halley's Comet1P/Halley
The most famous comet, visible from Earth every ~76 years, whose return in 1986 was met by an international fleet including ESA's Giotto — and the parent of two annual meteor showers.
TypeHalley-type cometPeriod76 yr - HyakutakeC/1996
The 'Great Comet of 1996', which passed very close to Earth and displayed one of the longest comet tails ever recorded.
TypeLong-period cometDiscovered1996Great cometYes - McNaughtC/2006
The 'Great Comet of 2007', the brightest comet in decades, whose vast fanned dust tail was a spectacular sight from the Southern Hemisphere.
TypeLong-period cometDiscovered2006Great cometYes - NEOWISEC/2020
The brightest comet visible from the Northern Hemisphere since Hale–Bopp, a naked-eye spectacle in July 2020 discovered by the NEOWISE space telescope.
TypeLong-period cometDiscovered2020Great cometYes - Siding SpringC/2013
A long-period comet that made an exceptionally close pass of Mars in October 2014, observed up close by the fleet of Mars orbiters and rovers.
TypeLong-period cometDiscovered2013 - Swift–Tuttle109P/Swift–Tuttle
A large Halley-type comet on a 133-year orbit, the parent body of the reliable Perseid meteor shower each August.
TypeHalley-type cometPeriod133 yrDiscovered1862 - Tempel–Tuttle55P/Tempel–Tuttle
The parent comet of the Leonid meteor shower, whose 33-year returns produce the periodic Leonid storms.
TypeHalley-type cometPeriod33 yrDiscovered1865 - ThatcherC/1861
A long-period comet on a roughly 415-year orbit, the parent body of the Lyrid meteor shower seen each April.
TypeLong-period cometPeriod415 yrDiscovered1861
Knowledge connections
- Reservoir ofHalley's Comet
- Reservoir ofComet Swift–Tuttle
- Reservoir ofComet Hale–Bopp
- Reservoir ofComet Hyakutake
- Reservoir ofComet NEOWISE
- Reservoir ofTempel–Tuttle
- Reservoir ofMcNaught
- Reservoir ofSiding Spring
- Reservoir ofThatcher
- ContainsInner Oort Cloud
Sources
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.