Skip to main content Skip to navigation

Kuiper Belt: What is it?

What is the Kuiper Belt? -Zaara A., 7, Deep Bay, Australia 

Dear Zaara,

You might say the Kuiper Belt is the frozen frontier of our solar system. Out beyond Neptune’s chilly orbit, this saucer-shaped region is home to Pluto, billions of comets, and other icy worlds.

“The Kuiper Belt is really the edge of knowledge,” said my friend and astronomy professor Guy Worthey when we met up in the Washington State University planetarium.

“Out there it’s a little dim,” Worthey said. “We are pretty far from the Sun.”

In fact, it’s about 3 billion miles away. Even at the speed of a jet airplane, it would take more than 680 years to travel from Earth to the outer solar system. Fortunately, spacecraft like NASA’s New Horizons can get there much faster.

Just last year, the world watched as New Horizons flew past Pluto and sent us the first up-close pictures of the dwarf planet. Now, it won’t be long before we head even deeper into the Kuiper Belt.

“Everything is going to be dark,” Worthey said. “But you’ll see these icy bodies. They’ll be of different sizes. There’ll be lots of little ones and some big ones.”

Screen Shot 2016-04-28 at 1.40.16 PMMany astronomers think there are 100,000 objects out there bigger than 60 miles wide, Worthey adds.

“They are sort of a dirty snowball composition,” Worthey said.

Just 15 years ago astronomers weren’t really sure if this part of the solar system even existed.

In the 1950s, Gerard Kuiper (KI-purr), a Dutch astronomer, was curious about comets, particularly where they were coming from and how they traveled through the solar system. He thought the outer solar system just couldn’t be empty.

About 40 years later, two scientists working at an observatory in Hawaii detected the first object in the Kuiper Belt aside from Pluto and its moon Charon. They had been looking for five years when they finally found an ice sphere more than 150 miles wide.

Ever since, astronomers have been using math and science to detect other distant objects. They’ve detected other dwarf planets like Pluto, including Eris, Haumea, and Makemake.

They’ve also found Plutinos that, like Pluto, are small worlds that have been caught in Neptune’s orbit.

“As you cruise by one of those things, they’ll look like spheres or worlds,” Worthey said. “They are quiet, they are on slow orbits.”

Astronomers are fascinated with these places for a couple of reasons. One is because the region may hold clues about the way solar systems form. Other scientists are particularly interested in the comets. Some wonder if some of these icy objects fell from the Kuiper Belt, and then melted in the Sun’s heat to form Earth’s oceans.

There’s also been a buzz about finding a new ninth planet in the Kuiper Belt or beyond. Though, there’s no proof of it yet, it’s an exciting prospect. If there is another planet in the Kuiper Belt, we’ll have to go find it with a spacecraft or a super huge, powerful telescope.


Dr. Universe

Pi: Why is it 3.14 and so on? What if it was just 3?

Why is Pi 3.1415…? What if it was just 3? -anonymous

Dear Curious Readers,

It’s almost March 14. You know what that means: Pi Day, as in 3/14, or 3.14159265359 and so on.

I met up with my friend Nathan Hamlin, a mathematician and instructor here at Washington State University, to explore your question about this never-ending number.

We calculated Pi with some of my favorite items: yarn and a tuna can. You can try it at home, too. » More …

Bones: How are they made?

How are bones made? -Oscar, 10

Dear Oscar,

A couple months before you were born, your skeleton was soft and bendy. It was made out of cartilage, the same material that’s in your nose and ears now. But when certain cells in your body called osteoblasts and osteoclasts began to work together, new bone started to form. » More …

Why do bees make hexagons?

Why do bees make hexagons in their hives? Why not any other shape? -Aditya, 10, New Delhi, India

Dear Aditya,

When bees make hexagons in their hives, the six-sided shapes fit together perfectly. In fact, we’ve actually never seen bees make any other shape. That’s what I found out when I visited my friend Sue Cobey, a bee researcher at Washington State University.

Cobey showed me some honeycombs where the female bees live and work. Hexagons are useful shapes. They can hold the queen bee’s eggs and store the pollen and honey the worker bees bring to the hive.Dr.UBees

When you think about it, making circles wouldn’t work too well. It would leave gaps in the honeycomb. The worker bees could use triangles or squares for storage. Those wouldn’t leave gaps. But the hexagon is the strongest, most useful shape. » More …

Do animals dream?

Dear Dr. Universe, Please answer this question: Do animals dream? What dreams do they get? I humbly request you to answer these questions. BYE! Or should I say MEOWY! -Prahlad R.

Dear Prahlad,

After a quick catnap and a stretch, I went to visit my friend Marcos Frank, a scientist at Washington State University who studies animal sleep.

» More …

How does my family car work?

Dear Dr. Universe: I want to know how my family car works. How does the gas reach the engine and go? How does the steering wheel make the car turn and how do the brakes help us to stop? -Jordan, 6, Queens, New York 

Dear Jordan,

As a cat, car rides can sometimes make me feisty. But as a scientist, it’s fascinating to learn about the mechanics, engineering, and chemistry fueling the cars humans drive every day.
» More …