Solar System Exploration
Join us as we explore our planetary neighborhood: The Sun, planets, moons, and millions of asteroids and comets.
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Solar System Overview
The solar system has one star, eight planets, five dwarf planets, at least 290 moons, more than 1.3 million asteroids, and about 3,900 comets. It is located in an outer spiral arm of the Milky Way galaxy called the Orion Arm, or Orion Spur. Our solar system orbits the center of the galaxy at about 515,000 mph (828,000 kph). It takes about 230 million years to complete one orbit around the galactic center.
We call it the solar system because it is made up 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 Pluto, Ceres, Makemake, Haumea, and Eris – along with hundreds of moons; and millions of asteroids, comets, and meteoroids.
Get Ready for the Total Solar Eclipse
On Monday, April 8, 2024, a total solar eclipse will cross North America, including a 108-to-122 mile wide path of the United States stretching from Texas to Maine.
Learn MoreOur Daily Skywatching Guide
A detailed guide to the night sky written by a NASA expert featuring full Moon lore, asteroid flybys, stars, galaxies, constellations, and more.
Learn More10 THINGS about our solar system
Saying Farewell: Which Spacecraft are Leaving Our Solar System?
Only two spacecraft have reached interstellar space, the space between stars. Three other spacecraft have achieved enough velocity to eventually travel beyond the boundaries of our solar system.
- Voyager 1 went interstellar in 2012 and Voyager 2 joined it in 2018. Both spacecraft, launched in 1977, are still in communication with Earth.
- NASA's New Horizons spacecraft is currently exploring an icy region beyond Neptune called the Kuiper Belt. It eventually will leave our solar system.
- Pioneer 10 and Pioneer 11 also will ultimately travel silently among the stars toward the galactic core. The spacecraft used up their power supplies decades ago.