Is it possible for planet to collide with one another?

Answer 1

In the early days of a solar system planetoids can collide with each other on a regular basis, but after the formation of regular planets with orbits, it would be hard to imagine a planetary collision. There would have to be a significantly influential gravitational force, perhaps from a passing star, to alter the orbit of a planet to set it on a collision course with another. We've seen examples of this with exoplanets, where one world's orbit was altered so much as to be made to orbit in the opposite direction of it's star's rotation.

Answer 2

It is possible for planets to collide with one another, although it is a very rare occurrence due to the vast distances between celestial bodies. When planets do collide, they can merge to form a larger planet or moon, or they can break apart into smaller fragments. This can have significant effects on the planets involved and the surrounding space environment.

Answer 3

• Around our sun? Now? No, the orbits are all too regular and the spaces between planets have been swept clean by near miss gravitational ejections and long past collisions.
• More than about 3.5 billion years ago when the spaces between orbits still contained many large protoplanetary bodies with very elliptical orbits: yes collisions were very possible.