Skip to main content Skip to navigation
Ask Dr. Universe Archives

Hey, Dr. Universe: Why do we humans get sunburns when we are out in the sun too long? - Gavyn, 13, Indiana 

Humans need sunlight to help keep their bones, blood and other body systems healthy, but too much time in the Sun can sometimes leave people with a sunburn. Sunburns often strike when the body gets too much of a type of light, called ultraviolet light, from the Sun. As your body recognizes there is too much ultraviolet light, it turns on a defense system. The immune system, which responds to invaders like viruses and other harmful things like ultraviolet light, kicks in. Some people might see their skin get red or blistered. They might feel itchy or painful. But not everyone experiences sunburn in quite the same way. A big part of the answer to your question also has to do with human cells. My friend Cynthia Cooper, a researcher at Washington State University, knows a lot about cells and how they work. Read More ...

Dr. Universe: How are coins made? -Dahlia, 10, Olympia, WA

In the United States, pennies, nickels, dimes, quarters, and other coins are made through the U.S. Mint. It turns out, they’ve been making a lot more coins than usual during the global pandemic. But more on that in a moment. It takes both science and art to make coins. Coins are made from metals that have been mixed together. We call these kinds of metals alloys. The very first coins in the world were made thousands of years ago in Turkey from electrum, an alloy of gold and silver. A penny is made from an alloy of copper and zinc. Read More ...

Dr. Universe: Why do we have a tailbone? -Tyler, 15, East Liverpool, England

Dear Tyler,

At the very bottom of the human spine is a bone that sticks out a bit called the coccyx (cox-ix). We sometimes call it the “tailbone,” but it is actually made up of several different spinal bones.

In some animals that actually have tails, those different bones at the bottom of the spine help them move their tail around. But in humans, those bones partially fused together.

Read More ...

Dear Dr. Universe: Why do flowers smell so nice? – Miles, 5

Flowers not only smell nice to humans, but also to many insects and birds who help the flowers do a really important job. Let’s imagine that you are a bee or a butterfly. You don’t have a nose on your face, but instead use your two antennae to smell things. As you fly around, you catch a whiff of chemicals floating in the air. Down below, you see a field of daisies. The flowers are releasing some chemicals, which are the building blocks of a smell. Read More ...

Dear Dr. Universe: How many different types of plankton are there? Are there freshwater plankton? – Arielle, 11

We can find millions and millions of plankton in bodies of water all over the world—from oceans, rivers, and lakes to ponds and mud puddles. That’s what I found out from my friend Julie Zimmerman, a scientist with the Aquatic Ecology Lab at Washington State University. In the lab, researchers can use powerful microscopes to get an up-close look at these tiny creatures. Read More ...

Why do we have different feelings? - Charan and Aishwarya V., 10 & 8, Rutherford, New Jersey

Dear Charan and Aishwarya,

Imagine you are playing a game of soccer and your best friend is on the opposing team. The sun is out, you are having a great time, and you score the winning goal. You’d probably feel pretty happy and so would your team.

Read More ...