Pluto and Eris are most likely members of which region?

• A. Asteroid belt
• B. Main belt
• C. Kuiper belt
• D. Oort cloud

Answer: (C)

Pluto and Eris are part of the Kuiper belt, a disc-shaped region beyond Neptune filled with icy bodies and dwarf planets. This area starts around 30 AU from the Sun and extends up to about 55 AU, so objects here are far outside the main planetary zone and are composed largely of ices rather than rock. That icy, distant, outside-Neptune nature is what defines Kuiper belt objects like Pluto and Eris. The asteroid belt sits between Mars and Jupiter and is mainly rocky, so it’s not where these objects belong. The Oort cloud is a distant, roughly spherical shell far beyond the Kuiper belt and is associated with long-period comets, not the main home of Pluto and Eris. So the best fit for Pluto and Eris is the Kuiper belt.