Editing Binary asteroid (section)

== Description ==

Several theories have been posited to explain the formation of binary-asteroid systems. Many systems have significant macro-porosity (a "[[Rubble pile|rubble-pile]]" interior). The satellites orbiting large [[Asteroid belt|main-belt asteroids]] such as 22&nbsp;Kalliope, 45&nbsp;Eugenia or 87&nbsp;Sylvia may have formed by disruption of a parent body after impact or fission after an oblique impact. [[Trans-Neptunian object|Trans-Neptunian]] binaries may have formed during the formation of the Solar System by mutual capture or three-body interaction. [[Near-Earth object|Near-Earth asteroids]], which orbit in the inner part of the Solar System, most likely form by spin-up and mass shedding,<ref name="binary NEAs">{{cite journal | doi=10.1126/science.1072094 | author=Margot, Jean-Luc | s2cid=8768432 | date=2002 | title= Binary Asteroids in the Near-Earth Object Population. | journal=Science | volume=296 | issue=5572 | pages=1445–1448 | pmid=11951001 |bibcode = 2002Sci...296.1445M |display-authors=etal}}</ref> likely as a result of the [[YORP effect]]. Numerical simulations suggest that when solar energy spins a “rubble pile” asteroid to a sufficiently fast rate by the YORP effect, material is thrown from the asteroid's equator.<ref name="Walsh08">{{cite journal|date=June 2008|title=Rotational breakup as the origin of small binary asteroids. |journal=Nature |volume=454|issue=7201 |pages=188–191|doi=10.1038/nature07078|author=Walsh, Kevin J.|pmid=18615078|last2=Richardson|first2=DC|last3=Michel|first3=P|bibcode = 2008Natur.454..188W |s2cid=4418744 }}</ref> This process also exposes fresh material at the poles of the asteroid.<ref name="Walsh08"/><ref>[http://newswise.com/articles/view/542454/ Study Puts Solar Spin on Asteroids, their Moons & Earth Impacts] Newswise, Retrieved 14 July 2008.</ref>