Our solar system consists of our star, the Sun, and everything bound to it by gravity – the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune; dwarf planets such as Pluto; dozens of moons; and millions of asteroids, comets, and meteoroids.

2025年1月9日 · NASA’s real-time science encyclopedia of deep space exploration. Our scientists and far-ranging robots explore the wild frontiers of our solar system.

Defining the term planet is important, because such definitions reflect our understanding of the origins, architecture, and evolution of our solar system. Over historical time, objects categorized as planets have changed.

2025年1月9日 · NASA’s real-time science encyclopedia of deep space exploration. Our scientists and far-ranging robots explore the wild frontiers of our solar system.

2025年1月9日 · We provide the public with reliable, accurate, up-to-date information about the planets, moons, asteroids, comets and everything else in our solar system. We also provide a complete historical record of deep space exploration.

The Sun is the largest object in our solar system. Its diameter is about 865,000 miles (1.4 million kilometers). Its gravity holds the solar system together, keeping everything from the biggest planets to the smallest bits of debris in orbit around it.

2025年1月9日 · Pluto was once our solar system's ninth planet, but has been reclassified as a dwarf planet. It's located in the Kuiper Belt.

2025年1月9日 · The Sun is the star at the heart of our solar system. Its gravity holds the solar system together, keeping everything – from the biggest planets to the smallest bits of debris – in its orbit.

In the 400 years since Galileo's discovery, the rings have become Saturn’s telltale feature and are perhaps the most recognized characteristic of any world in our solar system. Cassini spent more than a decade examining them more closely than any spacecraft has before.

Eris is one of the largest known dwarf planets in our solar system. It's about the same size as Pluto but is three times farther from the Sun. At first, Eris appeared to be larger than Pluto.