Question

Why do some astronomers object to the new definition of a planet that was adopted in 2006?

Answer 1

Answer:

A. New space missions show that Pluto is much larger than originally thought.

Explanation:

The new definition of a planet that was adopted in 2006, defined planet as  an object that orbits the sun, with sufficient mass to be round, not a satellite of another object, and has removed debris and small objects from the area around its orbit.

This new definition of a planet that was adopted in 2006, classified Pluto as "dwarf planet", because Pluto meets planetary criteria except that it has not cleared debris from its orbital neighborhood.

However, new Horizons spacecraft flew by Pluto in 2015, revealed that Pluto is much larger than originally thought

Therefore, the correct option is "A"

A. New space missions show that Pluto is much larger than originally thought.