Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid
These are organized by a classification scheme developed exclusively for Cosma. More…
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
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.
Hubble Telescope zooms in on interstellar visitor
on October 16, 2019 at 6:29 pm
The Hubble Space Telescope has captured the best pictures yet of our newest interstellar visitor.
The visible spectrum of C/2019 Q4 (Borisov), the...
on September 16, 2019 at 1:55 pm
Shortly before dawn on September 13th, Julia de León, Miquel Serra-Ricart, Javier Licandro, all members of IAC's solar system Group, and Carlos Raúl de la Fuente Marcos, from the Complutense University of Madrid, obtained high resolution images and visible spectra of comet C/2019 Q4 (Borisov) using the OSIRIS instrument at the 10.4m GTC, installed in the Roque de los Muchachos Observatory (Garafía, La Palma). Observations were not easy, as the object could only be seen at […]
'Oumuamua is not an alien spacecraft: study
on July 1, 2019 at 4:00 pm
On October 19, 2017, astronomers discovered the first known interstellar object to visit our solar system. First spotted by the Panoramic Survey Telescope and Rapid Response System 1 (PanSTARRS1) telescope located at the University of Hawaii's Haleakala Observatory, the object defied easy description, simultaneously displaying characteristics of both a comet and an asteroid.
ESA's new mission to intercept a comet
on June 20, 2019 at 12:44 pm
"Comet Interceptor" has been selected as ESA's new fast-class mission in its Cosmic Vision Programme. Comprising three spacecraft, it will be the first to visit a truly pristine comet or other interstellar object that is only just starting its journey into the inner Solar System.
Stolen comets and free-floating objects
on May 28, 2019 at 2:14 pm
Our solar system may contain alien comets that were stolen from another star flying past 4.5 billion years ago. Far away in a distant cluster of young stars, a similar close encounter might have also sent the inter-stellar visitor "Oumuamua" flying on its way toward us, and there must be many more of these free-floating objects in the galaxy. These are results of a new study by astrophysicists at the University of Zurich.