An object eight times the mass of Jupiter may have swooped around the sun, coming superclose to Mars' present-day orbit ...

Terrestrial planets include Mercury ... They are sometimes called gas giants because they are large and made mostly of gases. Small amounts of rocky materials are only found deep in the cores ...

A year on Uranus is 42,718 Uranus days long! Between the orbits of the terrestrial planets and the gas giants, there are millions of asteroids – rocky objects that orbit the Sun and vary in size ...

Interestingly, this all means there can be an overlap between the masses of the most massive planets and the least massive brown dwarfs. Additionally, gas giants can be larger in size than more ...