How Many Different Gases are in the Air?

There are a lot of gases in the air around us, but most of the air is made up of just three gases—nitrogen, oxygen, and argon. There are smaller amounts of carbon dioxide and water vapor. And there are about ten more gases in amounts so tiny that people seldom talk about them. Of course, the list doesn't stop, either. Anything that you can smell—like roses or cheese or onions—must have some chemical that is carried as a gas in the air. So if you want to think of things like that, then the list of gases in the air would go on and on. I hope you do not want me to name them all because I doubt that anyone really knows.

Why Do Sunburns Feel Hot?

Why do you feel hot when you get a sunburn? 

It is important to understand that a sunburn is a real burn. It occurs right in the skin surface because of damage caused by ultraviolet light. One of the results of the damage is to enlarge the tiny blood vessels just under the surface. That allows more blood to flow to the skin, making the skin look red and feel warm. It has happened to me, too, and it made me feel warm all over.

Is Octopus Ink Poisonous?

When alarmed or threatened, an octopus may squirt out a cloud of inky liquid. The cloud is like a smoke screen and allows an octopus to escape a potential predator. The brown or black cloud is inky because it contains a lot of melanin, a common pigment found in animals to give them color. Humans get their skin color from melanin.

The ink from an octopus may contain some chemicals that harm the smell receptors of animals, but it is not poisonous. 

Do Fish Sleep?

Yes, I would say that fish do sleep. Some fish actually lie on the bottom at night. Some of them even produce a gooey covering as a protection against other fish who might be looking for an easy meal. In the dark many fish have a lower rate of metabolism (their body machinery slows down), and that is much like sleep.

But there is one thing you do in your sleep that fish do not do. You close your eyes. Fish can’t do that. They don’t have any eyelids.

How Do Bees Make Honey

You may have seen honeybees buzzing around flowers. If you watch them without getting too close, you will see them crawl right down into a flower. They are searching for a few drops of the sweet nectar, or sugar water, that the flower makes.

The bee will carry a load of nectar from a lot of flowers back to the hive. Then the bees will use their wings to move a little draft of air to evaporate most of the water. What's left is honey.

Do Dogs Have Good Eyesight?

I always supposed that dogs have good eyesight. However, maybe some of them have problems with their eyes just as humans do.

I also should tell you that I have seen dogs bark at very strange things for no reason that I could understand.

Maybe you can invent some way to test your dog's eyesight. Will it run to get a stick or ball that you throw? If it can do that, its eyesight must be OK. Or maybe you can think of some other trick.

How Do Our Bones Keep Getting Bigger?

Bones that we see look hard and solid. In your body, bone is a living part of you. It has its own special blood supply and special cells for making or taking away the hard stuff, which is made mostly out of calcium and phosphate.

Throughout our lives our bones are slowly changing or being remodeled. At your age, your bones are increasing in size and length.

After middle age, bones tend to decrease in size and most people actually decrease a little in height.

Why Do We Shiver?

Shivering is a special way the body has of trying to warm up when it gets cold. Whenever your muscles are working, they are also giving off heat. You already know this because when you are running or playing hard you get warm. Then your body sweats, and this helps cool you by evaporation of the sweat.

When your body gets cold you can help it warm up by running or some other kind of exercise. If you do not do that, your body has its own automatic or reflex way of making muscles work just under your skin.

That is what we call shivering.

Why is the Desert Hot all day and then Cold all Night?

Most of the heat at Earth's surface comes from sunlight. During the day in a desert such as the Sahara, a lot of sunlight heats the ground, which then heats the air. At night, that heat escapes into space, which makes the temperature in the desert drop very low.

In areas that are not deserts, clouds prevent some sunlight from reaching the ground. That's why the days are not so hot. Clouds also stop much of the heat from radiating into space, which explains why the nights are not so cold.

How Come People Use Air to Blow Out Small Fires, But Also Use it to Make Large Fires Bigger?

I have noticed that, too. And at first it does seem to be a surprise. Air does two opposite things to a fire. It provides oxygen that is needed for anything to burn. If you keep air from getting to a fire, you can put it out.

Air also can cold down a fire. The flame and heat of the fire come from burning gases. A blast of air hard enough to keep the flame away from the fuel will put out a fire.

I guess this is another case of "a little is great, but too much is bad."

Why Does Cold Pop Get Warm but Hot Cocoa Get Cold?

It all depends on the way heat behaves: it always flows from someplace hotter toward someplace cooler. For something hot like cocoa, the heat flows from the cocoa to the air of the room. So the cocoa cools down. If you leave it overnight, it will become the same temperature as the surrounding air.

Room air is warmer than cold pop. So the heat flows from room air to the pop, and the pop warms up. If you leave the pop overnight, it will have time to reach the same temperature as the surrounding air ( and the cocoa).

How does the Earth Float in Space and not Fall?

If the earth were really alone, it would actually just float in space. There would be no place to fall to.

But the earth is not alone. Fortunately it is locked into an orbit around the sun, held there by the force of gravity. 

You can think of the earth's motion this way. It is always trying to fall toward the sun. Because it is whirling around the sun in a circular path, it is also always trying to whirl out into space.

Those two forces work against each other perfectly to keep the earth in its orbit.

When My Dad Strikes a Match, Why Does a Flame Appear?

 A match is a special kind of invention for making fire. The idea is the same as the old trick of twirling a stick round and round while pressing its end into a rounded-out spot in another piece of wood. The friction make the end of the stick get hot. If some easy-to-burn stuff like wood shavings is right there, it could get hot enough to being burning.