This composite image illustrates the size of PT1, a potential New Horizons target Kuiper Belt object (KBO) discovered by the Hubble Space Telescope, relative to the target of the European Space Agency’s Rosetta mission target, comet 67P/Churyumov–Gerasimenko (“C-G”), and the target of NASA’s NEAR/Shoemaker mission, near-Earth asteroid Eros. PT1 is much bigger than typical comets like C-G. However typical comets may be fragments of KBOs similar to PT1, and exploration of KBOs like PT1 may thus tell us much about the origin of comets. Scientists expect KBOs to be very different from similar-sized asteroids because the KBOs formed much farther from the Sun.
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
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