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Dr. Universe: How fast does a bunny hop? How long does a bunny live? Can a bunny swim? How many babies does a bunny have? -Rueben, 7, Pennsylvania

Bunnies are hopping all over our planet. Some hop through snow and deserts while others hop through wetlands and woods. There are lots of different kinds of rabbits and they are all a little different. For the most part, a bunny hops, or actually runs, anywhere between 25 and 45 mph That’s even faster than most house cats can run. Rabbits are related to another group of animals called hares. Actually, rabbits and hares are in the same family, Leporidae. Hares look a lot like rabbits, but they have much bigger ears and bigger feet. Read More ...

Dr. Universe: How do earthquakes happen? -Aescli E., 10, Utah

We’ve had a lot of earthquakes on our planet this year. Maybe you’ve learned about them from the news or felt one shaking up your own neighborhood. First, it is important to know a bit about the Earth’s outer layer, or crust. The crust is made of seven big pieces called “plates.” They are about 60 miles thick and sort of float on the molten rock beneath them. That’s what I found out from my friend Sean Long, a geology professor at Washington State University who knows a lot about earthquakes. Read More ...

Dr. Universe: Why do we have five fingers and five toes? -Eli, 11, Edinburgh, Indiana

Dear Eli, While humans may be one of the few animals that can give a high five, they are one of many with five fingers and toes. Humans are part of the primate family, which also includes monkeys, apes, and even lemurs. As a member of the family, you also have fingernails instead of claws and pads on your fingertips that help with your sense of touch. Read More ...

Why does caffeine make us stay up longer? -Cooper, 12

Dear Cooper, You’re right, caffeine can help us stay awake—but only for so long. To understand exactly why it works, it helps to know about one of my favorite things: sleep. All animals need rest to stay healthy. But sometimes humans don’t get quite as much sleep as they need. They might be tired during the day or have a lot of work to do. To feel more alert, they might drink a cup of coffee, tea, or soda. These kinds of drinks contain caffeine, a chemical and stimulant that can trigger changes in the body. Read More ...

How many suns are in the universe?

Hey cool cats, I’m Dr. Universe, here to answer your baffling science questions like this one. How many suns are in the universe? The sun is actually a star, our nearest star, but there are lots of stars out there. Maybe you’ve tried counting them before. One, two, three, four, five, six, seven stars make up the big dipper. Astronomers estimate that the human eye could spot about 9,000 stars. Of course, the Earth blocks our vision so we only see about half of those in the night sky. If we use binoculars, we could see even more stars, about 200,000 of them. A small telescope can help us see more than 15 million stars and even more powerful telescopes can help us look for other galaxies which are home to even more stars. Have you ever been stargazing? What did you see in the night sky? Tell us about it sometime at

Why do bees make hexagons in their hives?

Hey cool cats, I’m Dr. Universe, here to answer your baffling science questions, like this one. Why do bees make hexagons in their hives? When bees make hexagons in their hives, the six-sided shapes fit together perfectly. You know, if you think about it, other shapes wouldn’t work quite as well. Circles would leave gaps in the honeycomb. Squares and triangles wouldn’t leave gaps, but the hexagon works even better. The hexagon uses the least amount of material to hold the most weight. Bees can use these hexagons to store things. The queen bees eggs, pollen, and honey. For having never done a day of math homework in their lives, bees use some pretty creative geometry and engineering to build their headquarters. You can send your own science question to Dr. Universe at Washington State University. Visit

Do plants get sunburns?

Hey cool cats, I’m Dr. Universe here to answer your baffling science questions. Like this one, “Dear Dr. Universe, Why don’t plants get sunburns?” That’s a great observation. For as much time as plants spend outside, we don’t see too many with a sunburn. Plants need sun to grow, but not too much sun. Since they can’t move into the shade, put on a hat or sunscreen, they have their own way of staying safe in the sun. They make their own kind of sunblock. Of course, it isn’t much like the sunscreen you and I might use. Plants make their sunscreen out of a special combination of building blocks called molecules. They join together to make a compound, and block out ultraviolet light from the sun. It’s the kind of light that can cause damage to skin, or other living tissues. The compound still allows other kinds of sunlight to come through. That way, the plant can live and grow without getting fried in the sun. Send me a science question of your own at

What is slime?

Hey, cool cats. I’m Dr. Universe here to answer your baffling science questions like this one. What is slime? Our world is full of slime makers. Slugs make gooey trails. Bacteria create slippery slime in pipes. Slime in your joints helps protect your bones. Slime is between a solid and a liquid. It’s a non-Newtonian fluid. You can make it right at home. Dissolve a teaspoon of borax in a cup of water. In another bowl, mix together half a cup of liquid glue and half a cup of water. Then combine everything. The glue contains long chains of molecules. We call them polymers. You might think of them like cooked spaghetti noodles that are all tangled up. If we let the noodles dry out a bit, we’d see they’d start sticking to one another. What was once a free flowing liquid is now thickened by polymers, a fun slime you can mold, bounce, twist and stretch. Send me a science question of your own at

Why is the ocean salty?

Hey cool cats, I’m Dr. Universe, here to answer your baffling science question. Like this one. Dear Dr. Universe, why is the ocean salty? If we took all of the salt from our oceans and spread it over Earth’s surface, it would be almost 500 feet high. It all starts with rocks and dirt on land. Salt is one of the many minerals in rocks. A lot of it is the kind you might sprinkle on food, sodium chloride. As you might guess, it’s made up atoms called sodium and chlorine. Water is really good at dissolving salt. You can see this in action, just by adding a little salt to a cup of water. The chemical reaction in water, pulls different parts of salt away from each other. Streams and rivers help dissolve the salts from the rock and carry it into the ocean. But not all salt stays in the ocean. Find out where it goes. Or send me a science question of your own at