Have you ever wondered what makes something count as a planet? Scientists made three special rules that an object must pass to earn the name planet. If it misses even one rule, it does not make the team.

The first rule is that a planet must travel around the Sun. The second rule is that a planet must be big enough that its own gravity pulls it into a round, ball shape. Small lumpy rocks do not count.

The third rule is the trickiest one. A planet must clear its path, which means it has cleaned up most of the other rocks and objects near its orbit. A real planet is the boss of its own path around the Sun.

Pluto used to be called the ninth planet, way out past Neptune. But Pluto shares its crowded path with many other icy objects, so it does not clear its path. Because of that, scientists gave it a new name.

Pluto is now called a dwarf planet. A dwarf planet follows the first two rules but breaks the third one. It is round and it circles the Sun, but it is too small to clear all the objects out of its way.

Changing Pluto's name did not make it disappear; it is still a fascinating little world. Sorting objects into groups like this helps scientists understand and study our solar system better.