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There are millions of asteroids floating around the solar system. With so many of them, it should be no surprise that some are weirdly configured. A recent example of one of these weird configurations was discovered when Lucy, NASA\u2019s mission to the Trojan asteroids, passed by a main-belt asteroid called Dinkinesh. It found that Dinkinesh had a \u201cmoon\u201d \u2013 and that moon was a \u201ccontact binary\u201d. Now known as Selam, it is made up of two objects that physically touch one another through gravity but aren\u2019t fully merged into one another. Just how and when such an unexpected system might have formed is the subject of a new paper by Colby Merrill, a graduate researcher at Cornell, and their co-authors at the University of Colorado and the University of Bern.<\/p>\n
<\/p>\n The paper, in particular, looks at when the system might have formed and does so through modeling. A theory in asteroid formation called the binary Yarkovsky-O\u2019Keefe-Radzievskii-Paddack effect, which, since no one wants to say the full name, is shortened to the acronym BYORP. This model explains how binary asteroid systems happen in the first place.\u00a0<\/p>\n Essentially, the asteroid speeds up its rotation due to radiation pressure. Eventually, due to those rotational forces, it gets to a point where its gravity is no longer capable of holding all of its material on its surface, and some of that material is ejected out into space, eventually coalescing into a \u201cmoon\u201d for the slightly larger asteroid.<\/p>\n \n