Kuiper Belt – NASA Solar System Exploration
Arrokoth (visited by NASA’s New Horizons mission) and Pluto are both in the Kuiper Belt – a donut-shaped region of icy bodies beyond Neptune’s orbit. There may be millions of these icy objects, collectively referred to as Kuiper Belt Objects (KBO) or Transneptunian Objects (TNO), in this remote region of our solar system.
Similar to the Asteroid Belt, the Kuiper Belt is a region of remnants of ancient solar system history. Like the asteroid belt, it was also shaped by a giant planet, although it was more of a thick disc (like a donut) than a thin belt.
The Kuiper Belt is not to be confused with the Oort Cloud, which is a much more distant region of icy, comet-like bodies that surrounds the solar system, including the Kuiper Belt. The Oort Cloud and the Kuiper Belt are believed to be sources of comets.
The Kuiper Belt is truly a frontier in space – it’s a place we’re still beginning to explore, and our understanding is still evolving.
Go further. Explore the Kuiper Belt in depth ›
10 things to know about the Kuiper Belt
The Kuiper Belt is a region of space. The frozen worlds and known comets in both regions are much smaller than Earth’s Moon.
The Kuiper Belt is a donut-shaped ring of icy objects around the Sun, extending just beyond Neptune’s orbit of about 30 to 55 AU.
Short-lived comets (which take less than 200 years to orbit the Sun) originate from the Kuiper belt.
There may be hundreds of thousands of icy bodies over 100 km (62 miles) and about a trillion or more comets in the Kuiper Belt.
Space suit required
Some dwarf planets in the Kuiper Belt have thin atmospheres that collapse when their orbit takes them furthest from the Sun.
Several dwarf planets in the Kuiper Belt have moons.
World of the Ring
Egg-shaped Haumea is surrounded by a ring.
The first mission to explore the Kuiper Belt is New Horizons. It flew over Pluto in 2015 and is on its way to explore another world of the Kuiper Belt.
Cold and dark
It is not clear whether the worlds in this far, cold region are capable of supporting life as we know it.
Hypothetical planet X
Astronomers are looking for a possible planet that could explain the bizarre orbits of several Kuiper Belt objects. The nickname: Planet 9.
Frequently Asked Questions
Where is the Kuiper Belt?
The inner edge of the Kuiper Belt begins at orbit of Neptune, about 30 AU from the Sun. (1 AU, or astronomical unit, is the distance from Earth to the Sun.)
The main interior region of the Kuiper Belt ends about 50 AU from the Sun. Overlapping the outer edge of the main part of the Kuiper Belt is a second region called the Scattered Disc, which continues outward to nearly 1000 AU, with some bodies in orbits that go even further.
How was the Kuiper Belt created?
Astronomers believe the icy objects in the Kuiper Belt are remnants of the formation of the solar system. Similar to the relationship between the main asteroid belt and Jupiter, it is a region of objects that could have come together to form a planet if Neptune had not been there. Instead, Neptune’s gravity stirred this region of space so much that the small icy objects were unable to merge into a large planet.
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