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Why does stuff decay?

Dr. Universe: I have a ginormous question for you. How come non-biodegradable take like a million, billion, zillion years to decay? -Madeline C., age 8

Dear Madeline,

You’re right. It can take a really long time for some things to decay.

If we buried an apple peel in the backyard it might only take a few weeks to break down into the soil. But if we buried a plastic water bottle, it would probably still be there hundreds of years from now.

There are a lot of living creatures in nature that help break down things. In fact, our trash cans are almost like an all-you-can-eat-buffet for tiny creatures called microbes. Well, an almost all-you-can-eat-buffet. There are some things that they can’t really feast on. It all depends on what’s in our trash bins.

For billions of years, microbes have been munching on plants and animals. They’ve also had some help from fellow decomposers, like worms, flies, and fungi.

The environment where they work can also speed up or slow down the process. The conditions of dirt, air, water, temperature, and sunlight can change the speed of decomposition.

These decomposers are pretty great at breaking down a lot of things we find in nature. But they aren’t as good at breaking down some other materials, such as plastic.

To find out why, I visited my friend Shuresh Ghimire, a scientist who studies biodegradables at Washington State University. He is also really curious about finding ways to decrease the amount of plastic waste in our world, particularly on farms.

Plastics were introduced in the 1930s, he explained. Now, that may seem like a long time ago to us. But for microbes that have been around for billions of years, that’s still a pretty new material.

Both an apple peel and a plastic bottle are made up of different kinds of atoms. Those atoms are bonded and held together in different ways. In an apple, the bonds between atoms are pretty weak. Microbes don’t have to use a lot of energy to break them into smaller parts.

But the plastic bottle has really strong bonds—especially where a carbon atom bonds with another carbon atom. It makes the material sturdy, but it also makes it pretty indestructible. Most microbes don’t recognize these bonds as something they can break down, at least not yet.

“There is a possibility that evolution of microbes over many years in the future may enable more of them to recognize bonds in plastics,” Ghimire said.

In fact, a group of scientists in Japan recently discovered a microbe that looks to be pretty good at eating plastic. They might be able to help us manage some of the plastic waste, but we can help, too.

A water bottle might last hundreds of years buried underground or in a land fill, but it could have a new purpose in our own lifetime if we remember to reuse or recycle it.

Sincerely,
Dr. Universe

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.

Sincerely,

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 …