Our Solar System

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    Dec. 18, 2018: What a way to end the year! Here’s a quick recap of just some of the events from around our solar system this month:

    InSight lander on Mars as seen from orbit.
    The InSight spacecraft as seen from orbit by NASA's Mars Reconnaissance Orbiter. Credit: NASA/JPL-Caltech/University of Arizona

    It’s not over yet—next up is NASA's New Horizon’s historic flyby in the Kuiper Belt on New Year’s Eve.

    What is Our Solar System?

    What is Our Solar System?

    Our solar system is planetary system that orbits a star and all of the objects that travel around it—eight planets, dozens of moons and millions of asteroids, comets and meteoroids. Most stars host their own planets, so there are likely tens of billions of other solar systems in the Milky Way galaxy alone. We've discovered more than 2,800 planetary systems so far.

    The planetary system we call home is located in an outer spiral arm of the vast Milky Way galaxy. It consists of the Sun (our star) and everything that orbits around it. This includes the eight planets and their natural satellites (such as our moon), dwarf planets and their satellites, as well as asteroids, comets and countless particles of smaller debris. Explore Our Solar System ›

    Ten Things to Know

    Ten Things to Know About Our 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 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.

    Did You Know

    Did You Know?

    Five spacecraft have achieved enough velocity to travel beyond the boundaries of our solar system. Voyager 1 crossed into interstellar space in 2012. Voyager 2 and New Horizons are still active and will eventually transition to the space between the stars. Pioneers 10 and 11 also have reached escape velocity, but both spacecraft have been inactive for many years

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