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How big is the Kuiper Belt?

The Kuiper Belt is 12 billion kilometers

How Big is the Kuiper Belt?

Did you know that the Kuiper Belt is a gigantic ring of icy objects that wraps around our Solar System? It’s so massive that it’s 20 times as wide and 20 to 200 times as massive as the asteroid belt, the other major belt of objects in our Solar System! To really understand how big the Kuiper Belt is, we need to talk about astronomical units (AU). One AU is the distance from the Earth to the Sun, which is about 93 million miles (150 million kilometers). The Kuiper Belt starts at about 30 AU from the Sun, which is the orbit of Neptune, and extends to approximately 50 AU. In simpler terms, the Kuiper Belt is so wide that if you were to travel at the speed of light (which is the fastest speed possible), it would still take you over 5 hours to cross it!

Size Comparison of the Kuiper Belt

To help you visualize how big the Kuiper Belt is, let’s compare it to some other things in space.

  • The Asteroid Belt: The asteroid belt is like a little sibling to the Kuiper Belt. It’s only about 1 AU wide, whereas the Kuiper Belt is 20 times wider!
  • The Earth: The Earth is a tiny speck compared to the Kuiper Belt. If the Kuiper Belt was the size of a football field, the Earth would be about the size of a pea!
  • The Sun: The Sun is the largest thing in our Solar System, but the Kuiper Belt is so wide that it surrounds the Sun and all the planets!

What’s in the Kuiper Belt?

The Kuiper Belt is like a giant cosmic freezer, filled with small bodies made largely of frozen gases, such as methane, ammonia, and water. These objects are often referred to as “ices”. Most of the objects that astronomers recognize as dwarf planets, like Pluto, Haumea, Quaoar, and Makemake, call the Kuiper Belt home. Some of the moons of the Solar System, such as Neptune’s Triton and Saturn’s Phoebe, may have even originated from the Kuiper Belt!

The Discovery of the Kuiper Belt

The Kuiper Belt was named after Dutch astronomer Gerard Kuiper, who first suggested the existence of a belt like this in 1951. But it wasn’t until 1980 that another astronomer, Julio Angel Fernandez, suggested that a belt of comets might exist beyond Neptune. The actual discovery of the Kuiper Belt, however, is credited to astronomers David Jewitt and Jane Luu, who identified the first Kuiper Belt Object (KBO) in 1992. Since then, over a thousand KBOs have been discovered! So, the next time you look up at the night sky, remember that beyond the planets, beyond Neptune, there’s a giant ring of icy objects known as the Kuiper Belt. It’s a testament to just how vast and amazing our Solar System truly is!

Smaller By Category
Distance from Neptune to Sun
Neptune is the most distant known planet in the solar system. The distance from Neptune to the Sun is greater than the diameter of any known star!
WOH G64
I know... you're thinking, "WOH... that's a big star!" Well, I guess you're right, because it's one of the biggest known stars. WOH G64 is found in the Large Magellanic Cloud. There is a cloud surrounding the star that extends half of a light-year.
VY Canis Majoris
VY Canis Majoris is one of the largest known stars. It is so large that if it were placed in the Solar System, it would extend beyond the orbit of Saturn! It would take a plane 800 years to circle it once.
Larger By Category
Distance from Voyager 1 to Earth
Over the last 45 years, Voyager 1 has traveled to a distance of 23 billion kilometers, which is the furthest any man-made object has gone, and every day it gets 1.5 million kilometers further away! You can't see it, even if you stare really, really hard!
Light-Day
Even in just twenty-four hours, light manages to zoom across the distance of 26 billion kilometers. That is distance is further than any human or space probe has traveled.
Distance from Comet Hale-Bopp to Sun (farthest)
The comet Hale-Bopp gets so far from the Sun, the tug of the planets changes its furthest point each visit. Arriving this time took 4,200 years, and it will take another 2,400 years to make another orbit.