– 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 ...

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. The ice line. Advertisement. Article continues below this ad.

A new Tatooine-like planet outside the solar system may orbit two failed stars, scientists reported Wednesday. ... but heavier than gas giant planets. A light year is nearly 6 trillion miles.

Our solar system may have a ninth planet after all, researchers say. The possibility that an additional planet may be hidden far into the solar system was touted more than a century ago.

Indeed, other planets, dwarf planets and moons in our solar system do have seasonal cycles — and they can look wildly different from the ones we experience on Earth, experts told Live Science.