Oort Cloud

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Introduction1

Where does the solar system end? (Space Place, NASA)

Solar Wind (Wikipedia)
Heliosphere (Wikipedia)
Heliopause (Wikipedia)

Voyager Mission Current Status (NASA/JPL)

Encyclopedia

Oort cloud, named after the Dutch astronomer Jan Oort, sometimes called the Öpik–Oort cloud, is a theoretical cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from 50,000 to 200,000 AU (0.8 to 3.2 ly). It is divided into two regions: a disc-shaped inner Oort cloud (or Hills cloud) and a spherical outer Oort cloud. Both regions lie beyond the heliosphere and in interstellar space. The Kuiper belt and the scattered disc, the other two reservoirs of trans-Neptunian objects, are less than one thousandth as far from the Sun as the Oort cloud.

The outer limit of the Oort cloud defines the cosmographical boundary of the Solar System and the extent of the Sun’s Hill sphere. The outer Oort cloud is only loosely bound to the Solar System, and thus is easily affected by the gravitational pull both of passing stars and of the Milky Way itself. These forces occasionally dislodge comets from their orbits within the cloud and send them toward the inner Solar System.Based on their orbits, most of the short-period comets may come from the scattered disc, but some may still have originated from the Oort cloud.

Astronomers conjecture that the matter composing the Oort cloud formed closer to the Sun and was scattered far into space by the gravitational effects of the giant planets early in the Solar System’s evolution. Although no confirmed direct observations of the Oort cloud have been made, it may be the source of all long-period and Halley-type comets entering the inner Solar System, and many of the centaurs and Jupiter-family comets as well.
The existence of the Oort cloud was first postulated by Estonian astronomer Ernst Öpik in 1932. — Wikipedia

Oort Cloud (Eric Weisstein’s World of Astronomy, Wolfram Research)
Encyclopædia Britannica

Portal

Solar System Exploration: Oort Cloud (NASA)

Library

WorldCat, Library of Congress, UPenn Online Books, Open Library

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Participation

Education

Voyager 1 and 2: The Interstellar Mission (Space Place, NASA)
Oort Cloud (Cosmos4Kids)
Solar Wind (Cosmos4Kids)
Heliosphere (Cosmos4Kids)
Heliopause (Cosmos4Kids)

Course

Crash Course Astronomy (YouTube)

OER Commons: Open Educational Resources

News

Phys.org, NPR Archives

Book

ISBNdb

Government

Document

USA.gov

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More News …

Phys.org - latest science and technology news stories Phys.org internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.

  • 2029 will be the perfect year to launch a mission...
    on January 5, 2022 at 12:13 pm

    Object 90377 Sedna—a distant trans-Neptunian object known best for its highly elliptical, 11,390-year long orbit—is currently on its way toward perihelion (its closest approach to the sun) in 2076. After that, Sedna will swing out into deep space again and won't be back for millennia, making this flyby a once-in-a-lifetime (or, once in ~113 lifetimes) opportunity to study an object from the far reaches of our solar system. There are no missions to Sedna in the works just yet, but […]

  • Comets' heads can be green, but never their...
    on December 20, 2021 at 8:00 pm

    Every so often, the Kuiper Belt and Oort Cloud throw galactic snowballs made up of ice, dust and rocks our way: 4.6-billion-year-old leftovers from the formation of the solar system.

  • How to see comet Leonard, according to the...
    on December 14, 2021 at 12:24 pm

    Now is the best time to get a glimpse of Comet C/2021 A1, better known as Comet Leonard. It's named for its discoverer, Gregory Leonard, a senior research specialist at the University of Arizona Lunar and Planetary Laboratory.

  • Comet A1 Leonard brightens in December
    on November 29, 2021 at 12:19 pm

    Now is the time to start tracking Comet C/2021 A1 Leonard, as it starts its dawn dive sunward.

  • The biggest comet ever seen will get as close as...
    on October 15, 2021 at 3:30 pm

    A mega-comet—potentially the largest ever discovered—is heading from the Oort Cloud towards our direction. Estimated to be 100–200 kilometers across, the unusual celestial wanderer will make its closest approach to the Sun in 2031. However, the closest it will come to Earth is to the orbit of Saturn.

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Related

Here are links to pages about closely related subjects.

Knowledge Realm

Physical

“Fundamentals”
Law (Constant) Relativity
Force Gravity, Electromagnetism (Light, Color)
Matter (Microscope) Molecule, Atom (Periodic Table), Particle

“Space”
Universe (Astronomical Instrument)
Galaxy Milky Way, Andromeda
Planetary System Star, Brown Dwarf, Planet, Moon

Our Neighborhood
Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Trans-Neptunian Object
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid

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Notes

1.   The resources on this page are are organized by a classification scheme developed exclusively for Cosma.