摘要
Despite Pluto’s demotion to dwarf planet status,people are still attached to it.Scientists combined observations of Pluto from NASA’s New Horizons probe with observations of comet Churyumov-Gerasimenko from the European Space Agency’s Rosetta probe and found that Pluto’s nitrogen abundance matched the pattern of about a billion comets,which led to the theory that Pluto is made of about a billion comets.Yet they don’t know exactly when or where these comets originated.By studying the origin and orbit of comets,the author of this paper found that the material that condensed Pluto was mainly comets and dust ejected by Neptune,and the Kuiper Belt objects were condensed by material ejected by Neptune toward the outer side of its orbit.
