New ways to decide what makes a planet a planet. In the past, the International Astronomical Union (IAU) said a planet is something that orbits the Sun, is round because of its own gravity, and has cleared its path of other objects. But this definition had some problems, especially for planets outside our Solar System, called exoplanets.

A team of researchers, including Jean-Luc Margot from UCLA, Brett Gladman from the University of British Columbia, and Tony Yang from Chaparral High School, studied how to classify planets better. They found two key points: first, moons (or satellites) are different from planets, and second, a planet's ability to clear its orbit is very important.

They used a method called "clustering" to group objects in the Solar System. Clustering helps find patterns in data. They saw that moons and planets fall into different groups naturally. They also found that a planet's power to clear its orbit, called "dynamical dominance," is a good way to define a planet. If an object can clear its orbit of other debris over a long time, it can be called a planet.

The researchers proposed two new frameworks. One is similar to the old IAU definition but includes exoplanets. The other is simpler, based mainly on the mass of the object. They hope these new ideas will help scientists agree on what a planet is, both in our Solar System and beyond.

It helps us categorise the many kinds of objects in space better and shows that science is always changing as we learn more about our universe.