"Solar" System

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 named the "solar" system because our Sun is named Sol, after the Latin word for Sun, "solis," and anything related to the Sun we call "solar."

Our planetary system is located in an outer spiral arm of the Milky Way galaxy.

• 

  
  

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. Beyond our own solar system, we have discovered thousands of planetary systems orbiting other stars in the Milky Way.

10 Need-to-Know Things About the Solar System

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 150 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 orbit, including 24 astronauts who orbited 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 is the only spacecraft so far to leave our solar system. Four other spacecraft will eventually hit interstellar space.

FAQ: What Spacecraft are Headed into Interstellar Space?

Five spacecraft have achieved enough velocity to eventually travel beyond the boundaries of our solar system. Two of them reached the unexplored space between the stars after several decades in space.

• Voyager 1 went interstellar in 2012 and Voyager 2 joined it in 2018. Both spacecraft are still in communication with Earth. Both spacecraft launched in 1977.
• NASA's New Horizons spacecraft—currently exploring the an icy region beyond Neptune called the Kuiper Belt—eventually will leave our solar system.
• Pioneer 10 and Pioneer 11 also will ultimately travel silently among the stars. The spacecraft used up their power supplies decades ago.

---