Earth isn't alone in orbiting our sun; it's joined by a bunch of planets, moons, asteroids, and comets that we collectively ...

The universe is filled with billions of star systems. Located inside galaxies, these cosmic arrangements are made up of at least one star and all the objects that travel around it, including planets, ...

Test your knowledge on our solar system, from the biggest and smallest planets to the behemoth mountain on Mars. When you purchase through links on our site, we may earn an affiliate commission.