Question

Why was the discovery of Eris in 2005 problematic for Pluto’s then designation as a planet? (1 point) Responses Both Eris and Pluto are not solid objects, so astronomers realized that they could not be considered planets. Both Eris and Pluto are not solid objects, so astronomers realized that they could not be considered planets. Both Eris and Pluto have no satellites, so it seemed that this meant they should not be deemed planets. Both Eris and Pluto have no satellites, so it seemed that this meant they should not be deemed planets. Both Eris and Pluto are larger than Neptune and seem to keep expanding, so astronomers wondered if either should be a planet. Both Eris and Pluto are larger than Neptune and seem to keep expanding, so astronomers wondered if either should be a planet. Both Eris and Pluto are part of the Kuiper Belt, so if Pluto was considered a planet, astronomers wondered if Eris should be as well.

Answer 1

The discovery of Eris in 2005 was problematic for Pluto's designation as a planet because both Eris and Pluto are part of the Kuiper Belt, so if Pluto was considered a planet, astronomers wondered if Eris should be as well. This raised the question of how to define what constitutes a planet, leading to a re-evaluation of Pluto's status.