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Another way of understanding the vastness of interstellar distances is by scaling: One of the closest stars to the Sun, Alpha Centauri A (a Sun-like star that is one of two companions of Proxima Centauri), can be pictured by scaling down the Earth–Sun distance to one meter (3.28 ft). On this scale, the distance to Alpha Centauri A would be ...
The interstellar medium is composed of multiple phases distinguished by whether matter is ionic, atomic, or molecular, and the temperature and density of the matter. The interstellar medium is composed primarily of hydrogen, followed by helium with trace amounts of carbon, oxygen, and nitrogen. [1] The thermal pressures of these phases are in ...
Interstellar object. An interstellar object is an astronomical object (such as an asteroid, a comet, or a rogue planet, but not a star or stellar remnant) in interstellar space that is not gravitationally bound to a star. This term can also be applied to an object that is on an interstellar trajectory but is temporarily passing close to a star ...
The visible shells of circumstellar material were ejected by the central star over thousands of years. One of the richest sources for detecting interstellar molecules is Sagittarius B2 (Sgr B2), a giant molecular cloud near the centre of the Milky Way. About half of the molecules listed below were first found in Sgr B2, and many of the others ...
Cosmic dust – also called extraterrestrial dust, space dust, or star dust – is dust that occurs in outer space or has fallen onto Earth. [1][2] Most cosmic dust particles measure between a few molecules and 0.1 mm (100 μm), such as micrometeoroids (<30 μm) and meteoroids (>30 μm). [3] Cosmic dust can be further distinguished by its ...
The heliosphere is the magnetosphere, astrosphere, and outermost atmospheric layer of the Sun. It takes the shape of a vast, tailed bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding interstellar medium. The "bubble" of the heliosphere is continuously "inflated" by plasma originating from ...
The Oort cloud (/ ɔːrt, ʊərt /), [1] sometimes called the Öpik–Oort cloud, [2] is theorized to be a vast cloud of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years). [3][note 1][4] The concept of such a cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in whose honor ...
Artist's view of the theoretical Oort cloud, Hills cloud, and Kuiper belt (inset) In astronomy, the Hills cloud (also called the inner Oort cloud [1] and inner cloud [2]) is a theoretical vast circumstellar disc, interior to the Oort cloud, whose outer border would be located at around 20,000 to 30,000 astronomical units (AU) from the Sun, and whose inner border, less well defined, is ...