Answer:
The criteria that astronomers use to classify an object as a planet is Its gravity makes the object spherical.
Explanation:
There are three principal criteria to determine if an object can be considered a planet:
* It must independently orbit the Sun
* It must have enough mass so that gravity pulls it into a roughly makes it take a spheroidal shape
* It must be large enough to "dominate" its orbit, it must be bigger than any object that crosses it.
