Oort Cloud

TECHNICAL DEFINITION

The Oort Cloud is a theoretical spherical shell of icy planetesimals believed to surround the Sun at distances ranging from 2,000 to 200,000 AU, serving as the primary reservoir for long-period comets.

BACKGROUND

Outer space, or simply space, is the expanse that exists beyond Earth's atmosphere and between celestial bodies. It contains ultra-low levels of particle densities, constituting a near-perfect vacuum of predominantly hydrogen and helium plasma, permeated by electromagnetic radiation, cosmic rays, neutrinos, magnetic fields and dust. The baseline temperature of outer space, as set by the background radiation from the Big Bang, is 2.7 kelvins.

SYNONYMS & ALIASES

• Comet reservoir
• Outer solar system
• Theoretical cloud
• Distant icy shell

USAGE NOTE

Long-period comets are thought to originate from the Oort Cloud.

DEVELOPERS

Organizations developing technology related to Oort Cloud.

• NASA Jet Propulsion Laboratory (JPL)

  Manages missions like the Voyager spacecraft, which are on a trajectory to eventually reach the Oort Cloud, and leads conceptual studies for future missions like the Interstellar Probe, which would directly sample this region.

• European Space Agency (ESA)

  Currently developing the Comet Interceptor mission, which is designed to perform a flyby of a pristine, long-period comet, a type of object that originates directly from the Oort Cloud.

• Johns Hopkins University Applied Physics Laboratory (APL)

  Leads the design and conceptual development of NASA's Interstellar Probe, a proposed robotic spacecraft designed to travel through the Oort Cloud to study its characteristics and the interstellar medium beyond.

• Vera C. Rubin Observatory

  A next-generation astronomical observatory whose Legacy Survey of Space and Time (LSST) is projected to discover and catalog tens of thousands of new comets, vastly increasing the known population of objects from the Oort Cloud.

• Southwest Research Institute (SwRI)

  Conducts extensive research and modeling of solar system formation and dynamics, including the Oort Cloud. SwRI scientists also develop instruments for missions that study comets and other small bodies.

• The Planetary Science Institute (PSI)

  A non-profit research organization whose scientists are heavily involved in studying the properties and origins of comets. They use data from telescopes and space missions to model the structure and population of the Oort Cloud.

• Minor Planet Center (MPC)

  The official international body for observing and cataloging asteroids and comets. The MPC operates the critical database and software systems that identify and track newly discovered comets, including those on long-period orbits from the Oort Cloud.