IntroductionShortly after midnight Eastern Time on Jan. 1, 2019, NASA’s New Horizons spacecraft will buzz by the most primitive and most distant object ever explored. New Horizons’ encounter with Kuiper Belt object 2014 MU69, which orbits a billion miles beyond Pluto, will offer the first close-up look at such a pristine building block of the solar system.

    New Horizons will fly about three times closer to MU69 than it did to Pluto in July 2015, allowing the spacecraft’s cameras to provide a more detailed look at the object’s surface.

    Both 2014 MU69 and Pluto are in the Kuiper Belt, is a disc-shaped region beyond Neptune that extends from about 30 to 55 astronomical units (compared to Earth which is one astronomical unit, or AU, from the Sun). Comets from the Kuiper Belt, known as short period comets, take less than 200 years to orbit the Sun and travel approximately in the plane in which most of the planets orbit the Sun. There may be hundreds of thousands of icy bodies and a trillion or more comets in this distant region of our solar system. Explore the Kuiper Belt ›

    Ten Things to Know About the Kuiper Belt

    Ten Things to Know About the Kuiper Belt


    Distant Destination

    The Kuiper Belt is a region of space. The known icy worlds and comets in both regions are much smaller than Earth's Moon.


    Cosmic Doughnut

    The Kuiper Belt is a doughnut-shaped ring of icy objects around the Sun, extending just beyond the orbit of Neptune from about 30 to 55 AU.


    Long Trip

    Short-period comets (which take less than 200 years to orbit the Sun) originate in the Kuiper Belt.


    Big Count

    There may be hundreds of thousands of icy bodies larger than 100 km (62 miles) and an estimated trillion or more comets within the Kuiper Belt.


    Spacesuit Required

    Some dwarf planets within the Kuiper Belt have thin atmospheres that collapse when their orbit carries them farthest from the Sun.


    Tiny Moons

    Several dwarf planets within the Kuiper Belt have moons.


    Ring World

    Egg-shaped Haumea has a ring around it.


    First Look

    The first mission to explore the Kuiper Belt is New Horizons. It flew past Pluto in 2015 and is on its way to explore another Kuiper Belt world.


    Cold and Dark

    It is not clear if worlds in this distant, cold region are not capable of supporting life as we know it.


    Hypothetical Planet X

    Astronomers are searching for a possible planet that might explain the strange orbits of several Kuiper Belt Objects. The nickname: Planet 9.

    Did You Know

    Did You Know?

    If it exists, hypothetical Planet X/Planet 9 may take between 10,000 and 20,000 Earth years to make one full orbit around the sun.



    Kuiper Belt and Oort Cloud Lithograph - 2013

    Dust Models Paint Alien's View of Solar System

    University of California at Los Angeles' Kuiper Belt Page

    New Horizons Mission to Pluto and the Kuiper Belt

    Hubble Space Telescope

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