Question

Shelly was surprised to learn the dwarf planet Pluto used to be considered a planet. What would have had to be true for Pluto to remain categorized as a planet?

Answer 1

Pluto would need to clear the neighborhood of its orbit would be your answer, hope this helps! :D

Answer 2

The answer is: Pluto would need to clear the neighborhood of its orbit.

Pluto is a dwarf planet in the Kuiper belt.

According to the International Astronomical Union a planet must satisfy the following three criteria:

1) Planet must have enough mass that its own gravity pulls it into a roughly spheroidal shape.

2) Planet must be an object which independently orbits the Sun.

3) Planet must be large enough to dominate its orbit, its mass must be much larger than anything else which crosses its orbit.