Discover the order of planets in the solar system. From Mercury to Neptune, explore our solar system and learn more about our cosmic home.

– Gavriel, age 10, Paducah, Kentucky A cloud of collapsing gas created our Sun, the first thing to form in our solar system. This happened about 4½ billion years ago. Then the planets began to ...

Our solar system is made up of the sun and all the amazing objects that travel around it. Learn more about the planets, asteroids, and comets in our solar system. 3:55. Solar System 101.

For years, astronomers have been searching for a mysterious ninth planet lurking in the dark outer reaches of our solar ...

Close stellar encounters could change the structure of our planetary system, potentially dooming Earth or other worlds to oblivion ...

How big it is: 865,000 miles (1.392 million kilometers) across How far away it is: 93 million miles (150 million km) What type of star it is: A yellow dwarf star The sun is the star at the center of ...

All eight of the solar system’s “major” planets appear in this illustration, but the actual number of planetary bodies orbiting our star is far greater. Digital Vision/Getty Images.

This process, called accretion, is how everything in the solar system – planets, moons, comets and asteroids – came into being. Telescopes can see young solar systems being born.

This process, called accretion, is how everything in the solar system – planets, moons, comets and asteroids – came into being. Advertisement Article continues below this ad ...

This process, called accretion, is how everything in the solar system – planets, moons, comets and asteroids – came into being. Advertisement Article continues below this ad ...