Do you have a question?

Fact 4

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Do you have a question?

Glossary

twinkle: (v.) shine with a gleam that changes constantly from bright to faint (opacity). Are you interested in science? Do you like finding out how things work? Do you want to know why things are the way they are? Here are some typical questions young people ask. Do you know the answers? What is a star? Why do stars ‘twinkle’? Why do my fingers go wrinkly in a pool? What is a molecule? Why does water in a lake look blue? Do dogs see color? How does a periscope work?

Let’s start with the question: Why do my fingers go wrinkly in the pool? The answer is simple. Your skin is covered with a special oil called sebum. This is on the very top layer of your skin and it makes your skin ‘waterproof’. It keeps the water out. But what happens when you spend a long time in the water? The oil is washed away, and the water can get into the outer layer of skin. So why do your fingers look all wrinkly? They have too much water in them. The extra water in your fingers makes your skin swell in some places but not others, and that’s what causes the wrinkles. Wrinkly fingers happen of course any time you have your hands in water for too long, not just in the swimming pool. And as you know, there is no reason to worry, because after a little while your fingers go back to normal. Glossary wrinkle: (n.) a slight line or fold in something, especially fabric or the skin.

What about the question: Do dogs see colors? Yes, dogs see colors, but the colors that they see are fewer and different from the colors you see. They don’t see the rainbow as violet, blue, blue-green, green, yellow, orange and red. They see it as dark blue, light blue, gray, light yellow, browny-yellow and very dark gray. In other words, dogs see the world as basically yellow, blue and gray.

Glossary

sweat: (v.) to perspire, especially freely or profusely.

While we’re on the subject of dogs, why do they have wet noses? The answer is, a wet nose helps them identify different smells in their environment. Remember that a dog has an incredible sense of smell, hundreds of times better than our sense of smell. Wet noses are also one of the ways that dogs can regulate body temperature and cool down. Dogs don’t sweat like we do, they only do it through their noses, their tongues and through the pads of their feet!

Why does the water in lake (a river, an ocean) look blue? It’s all about the reflection of light. When white light from the sun enters the ocean, it is mostly the blue that gets returned or reflected, and that’s why it looks blue to us. Put in another way, the colors red, orange and yellow are absorbed more strongly by water than blue. This is the same reason that the sky is blue.

Talking of the sky takes us to our next question, which is: What is a Star? For thousands of years when people looked up into the night sky, they had the same question. Now we know. Stars are balls of hot, explosive gas, mostly hydrogen and helium. They make their own light and heat energy through explosions that burn hydrogen and turn it into helium by a process called nuclear fusion!

Glossary

beam: (n.) ray of light. Have you ever looked up into the night sky and been amazed by the hundreds of ‘twinkling’ stars? In fact stars don’t really twinkle. They just look as if they do from our position on the Earth. What’s the reason? As their light beams down through the layers of our atmosphere, it bounces around, making it look strong one moment and weak the next. It looks like the stars are twinkling.

On to our next question: How does a periscope work?

We all know that a periscope is something we can use to look at things, like when you are in a submarine and want to know what’s on the surface of the water. Or when you’re playing and want to see around the corner. Did you know that in the 1430’s some pilgrims were given periscopes by a man called Johann Gutenberg so they could see objects over the heads of other people at a religious festival? The periscope is not a new instrument!

So back to the question. The answer is that a periscope has a long tube with parallel mirrors located at both ends at a 45º degree angle. When you look at something, a ball for example, you see it because light bounces off the ball into your eye. If the ball is around the corner, you can’t see it. But you CAN see it with a periscope because the mirrors bounce the light into your eye!

Any time two atoms join together, they make a molecule. All the stuff around you is made up of molecules. You are made up of molecules too! In fact, you are made up of trillions and trillions of different types of molecules.

Molecules are not only made up of different types of atoms but also different ‘ratios’. For example a water molecule has 2 hydrogen atoms and 1 oxygen atom. That is why it is written as H2O.

We’ve answered all the questions we started with. But here’s another one. What killed the dinosaurs? They existed for 165 million years so why did they suddenly disappear? Scientists have many different theories, but the most popular one is this: a massive asteroid hit the earth at Chicxulub on the Yucatan Peninsula in Mexico about 65 million years ago.

Scientists have worked out that the asteroid was very big! About ten kilometers across! They know this by measuring the crater it made. It is 180 km from side to side. An impact like that would have caused a giant cloud of dust. With so much dust in the air plants couldn’t grow. The plant eating dinosaurs had nothing to eat and died. The meat eating ones soon didn’t have any food either because the dinosaurs they ate died!

You can check out more about the extinction of dinosaurs and about any of the other topics you’ve read about here on the internet or in books. It is always good to ask questions and try to find out the answers. We hope you enjoy the search!