Question

1. why was ceres not considered a planet even though it orbits the sun?

Explanation:

To be classified as a planet, an object must meet three criteria: orbit the Sun, have sufficient mass for hydrostatic equilibrium (rounded shape), and clear its orbital neighborhood of other debris. Ceres, located in the asteroid belt, does not clear its orbital path (shares the region with many asteroids) and is now classified as a dwarf planet.

Answer:

Ceres is not considered a planet because it does not clear its orbital neighborhood (it shares the asteroid - belt region with numerous other celestial bodies) and is classified as a dwarf planet, as it fails to meet all the criteria for planethood (orbiting the Sun, hydrostatic equilibrium - met, but not clearing the orbit).