Plane of the Ecliptic: A perfect lineup of Mercury, Mars, Saturn and the corona of our Sun are captured in this Clementine spacecraft image of Earth's moon.

Our Solar System in Brief
Our solar system formed around our star - the Sun - about 4.6 billion years ago. There are eight planets, 146 moons, numerous asteroids and comets and intriguing dwarf planets such as Pluto and Ceres. The four planets closest to the Sun - Mercury, Venus, Earth and Mars - have solid, rocky surfaces. The four outer planets consist of two gas giants - Jupiter and Saturn - and two ice giants - Uranus and Neptune.

Featured Mission: Voyager 1
Voyager 1 has traveled farther from the Sun than any other spacecraft. Launched in 1977, the spacecraft is on an extended mission to help define the boundaries of our solar system.

Read More About About Our Solar System