The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

All seven of the other planets in our solar system are about to become visible at once in a great planetary alignment – ...

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

When astronomers found a large world farther out than Pluto, it became one of the final nails in the coffin of our ninth ...

However, this year a powerful new telescope is coming online that could prove once and for all that there really is a ninth planet in our Solar System. The same year that Pluto was ignominiously ...

Plate tectonics give Earth its mountains, earthquakes, continental drift and maybe even helped give rise to life itself. But ...

The James Webb Space Telescope has provided groundbreaking insights into a new type of exoplanet, fundamentally different ...