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Our Solar System
Why is it Called the Solar System?
There are many planetary systems like ours in the universe, with planets orbiting a host star. Our planetary system is called “the solar system” because we use the word “solar” to describe things related to our star, after the Latin word for Sun, "solis."
Our planetary system is located in an outer spiral arm of the Milky Way galaxy.
10 Need-to-Know Things About the Solar System
1. ONE OF BILLIONS
Our solar system is made up of a star, eight planets, and countless smaller bodies such as dwarf planets, asteroids, and comets.
2. MEET ME IN THE ORION ARM
Our solar system orbits the center of the Milky Way galaxy at about 515,000 mph (828,000 kph). We’re in one of the galaxy’s four spiral arms.
3. A LONG WAY ROUND
It takes our solar system about 230 million years to complete one orbit around the galactic center.
4. SPIRALING THROUGH SPACE
There are three general kinds of galaxies: elliptical, spiral, and irregular. The Milky Way is a spiral galaxy.
5. GOOD ATMOSPHERE(S)
Our solar system is a region of space. It has no atmosphere. But it contains many worlds – including Earth – with many kinds of atmospheres.
6. MANY MOONS
The planets of our solar system – and even some asteroids – hold more than 200 moons in their orbits.
7. RING WORLDS
The four giant planets – and at least one asteroid – have rings. None are as spectacular as Saturn’s gorgeous rings.
8. LEAVING THE CRADLE
More than 300 robotic spacecraft have explored destinations beyond Earth's orbit, including 24 American astronauts who made the trip from the Earth to the Moon.
9. LIFE AS WE KNOW IT
Our solar system is the only one known to support life. So far, we only know of life on Earth, but we’re looking for more everywhere we can.
10. FAR-RANGING ROBOTS
NASA’s Voyager 1 and Voyager 2 are the only spacecraft to leave our solar system. Three other spacecraft – Pioneer 10, Pioneer 11, and New Horizons – will eventually hit interstellar space.