A sentient planet is a planet that is alive. So far nobody knows how this happens. There are many different abilities caused by unknown variables. Sometimes they can only observe and talk with what's on the planet's surface, sometimes they can control what happens on the planet's surface, and sometimes they are capable of travelling through space on their own. Sometimes the planet will make an attempt to disguise itself as a regular planet. It ranks as Type 15 on the Planetary Classification scale.