Grass is green because a chemical in the grass called chlorophyll uses all the other colors to make energy for the leaves. The green light - which is not used - is therefore reflected off the grass and into your eyes, making the grass look green.

 

The sky is blue because there are tiny dust particles in the atmosphere that scatter blue light more than red light. As the sun's light passes through our atmosphere, the blue light bounces off the dust particles in all directions. When we look up at the sky we see blue because of all the blue light that is bouncing off the dust. This also explains why the sky is reddish-orange at dusk! When the sun goes down near the horizon, the sunlight must travel a longer distance through the atmosphere. Since the blue light is scattered, only the reddish-orange light gets through!

 

Although we do not know for sure, we believe it is because a LONG time ago, when the Earth was young, an asteroid hit the Earth and split the Earth's mass into two pieces. The smaller piece (moon) revolves around the bigger one (Earth now).

 

We can do a LOT to help the earth. One of the best things we can do is to not be wasteful. We can take a little less time in the shower, and not run the air conditioner or heater so much. This saves fuel and therefore reduces pollution. We can replant trees when we cut them down for wood and paper. These are just a few examples.

 

During the day, when the sun is shining, water evaporates and becomes a part of the air you breathe. The amount of water in the air is called "humidity." Warm air can hold more water than cold air, so when the sun sets and the air cools, the extra water has to go somewhere. Leaves of grass actually help the earth cool faster than patches of dirt without grass, so a lot of the extra water collects on the cooler grass, forming dew.

 

Underneath the outer surface, or crust, of the Earth there is a layer of rock that is so hot it is a liquid! Sometimes, this layer can push up through the crust and make a mountain. Once the mountain is formed, there might be a thin layer of solid rock holding back all of that hot liquid rock. Eventually, too much liquid pushes through the solid rock and gets shot high into the air, which is called an eruption. Some times, eruptions can be huge and blow apart the mountain. Sometimes, they can be calm and beautiful with red rivers of molten rock flowing down the side of a mountain and into the ocean. You can get more information about volcanoes at http://volcano.und.nodak.edu/vw.html

 

Many astronauts started as pilots of airplanes and love to fly. Others are doctors or scientists. They go into space to repair satellites or conduct neat science experiments where there is no gravity. Some new medicines can be created in space much easier than on the earth. Astronauts are also explorers of the unknown. They are very curious about what is in space.

 

The ocean has salt in it because of the salt that hides in rocks on land. When it rains, the rainwater is usually acidic, which means it can slowly dissolve almost everything on Earth - Including the Earth itself! The rainwater carries the salt from the rocks into the oceans.

 

Actually, it does pull Mars. If the sun's gravitational pull didn't pull on Mars, Mars would not be orbiting the sun and would have floated away a long time ago. It is because of the pull of the sun that Mars continues to follow an orbit and circle the sun just like all the other planets. The reason Mars doesn't get closer and closer to the sun is because it is already moving in an orbit. If it stopped moving, the gravitational pull would pull the planet into the sun, just as gravity on earth pulls you to the ground.

The answer depends on how fast the spaceship is going and exactly where in "outer space" you are trying to go. There is no exact point where the Earth's atmosphere ends and the vacuum of space begins but many scientists say that our atmosphere ends about 660 miles above the surface of the Earth.

The Apollo 8 Spaceship made it from the moon back to Earth in only 54 hours! However, if you were trying to get to the nearest star, Proxima Centauri, it would take a little bit longer. The Galileo spaceship achieved a speed of 60,000 miles per hour, but even at this speed, it would take over 44,500 years to make it to the nearest star!

To give you an idea of how fast these shuttles are moving, after the two minute main burn at the beginning of a ship's launch, the shuttles are going more than 20,000 miles per hour. This is the same as 5.5 miles per second which is ten times faster than a bullet! So as you can see, space travel depends a lot on how fast the ship is going and how far away the destination is, but space shipes are getting faster and better able to travel long distances so we will constantly be able to explore new parts of our solar system as long as scientists remain hard at work.

 

If this story is true, that man is very lucky! The point of the tornado drill position, when you crouch on the floor facing a wall and cover your head, is to stay as close to the ground as possible and to protect your head from flying objects. If you're picked up by a tornado and you hold onto a mattress, it will only protect one side of you. If this man were to fall forward or a flying object were to head towards him, the mattress behind him wouldn't help at all. Actually, he might be hurt even more if he fell forward, because the heavy mattress would fall on top of him. So the answer to your question, Amanda, is yes and no. It might protect you if you're lucky, but it might not. The best thing to do is to stay away from any windows, crouch near a wall with your head down, and cover the back of your neck with your hands.

 

Yes! This is why plants are very important to us. The leaves on trees contain a green chemical called chlorophyll that, when exposed to light, takes carbon dioxide (the gas that comes from our lungs when we breathe out) and water, and turns it into oxygen and food for the tree. This oxygen is then released from the leaves into the air. This process of turning carbon dioxyde and water into oxygen is called photosynthesis, a word that means "creating compounds using light". All green plants contain chlorophyll and release oxygen in the sun. Some trees do this only in the summer and drop their leaves in autumn; these are called deciduous trees. Other trees have leaves or green needles that are on the tree year round, and they are called coniferous trees. They create oxygen throughout the year when it's sunny.

 

The sun is one very large ball of extremely hot gases. These gases are constantly changing from one form to another in many chemical reactions. A nuclear reaction in which hydrogen is fused to form helium occurs, and this releases a huge amount of heat and light. Scientists are now able to produce this reaction on earth and this will likely be our next source of energy on the planet.

 

There are two ways the earth moves. First, the earth rotates, which is a spin around its own axis. This motion takes 24 hours and it results in daytime and nighttime. Second, the earth revolves in an orbit around the sun. This motion takes 1 year and, due to the earth's spinning that is a little off-center, creates the seasons.

If the earth just stopped revolving around the sun but continued to rotate, we would still have day and night, but we would be stuck in one season forever.

If the earth stopped revolving around the sun AND stopped rotating, we would be stuck in one type of season as well as one time of day. Some parts of the earth would be sunny all the time and others would be dark all the time. This would not be good, because it would cause the sunny part to turn into dry desert and the dark part to freeze. So it's good that the earth rotates and revolves!

 

Clouds are made up of water vapour, which is tiny water droplets floating in the air. These droplets are small enough to float, but large enough that a bunch of them together can be seen. There is water in the air around you, but it is too spread out and too small for you to see it. A cloud is a slightly more dense amount of water, with the droplets large enough and close enough together that you can see them. Clouds are also made up of tiny particles of dust and smoke, which the water droplets stick to. This means that in each drop of water in a cloud and in each drop of rain, there are tiny particles of dust that let the droplet form. People can even drop dust onto clouds from airplanes, which causes the drops to get bigger and make it rain. This process is called "seeding".

 

Very fast! The most violent tornadoes that we know of can have wind speeds of 250 miles per hour or more! This is equal to ten times, or 1000% the speeds you drive in Hillsborough (assuming you drive about 25 miles per hour downtown)! The highest wind speeds ever measured from a tornado were in Oklahoma on May 3rd, 1999: these tornadoes had wind speeds of approximately 318 miles per hour!

 

The hurricanes with the fastest moving winds were Hurricane Camille (1969) and Hurricane Allen (1980) that had winds speeds estimated at 190 miles per hour. These measurements are approximations because wind speeds like that can damage or destroy regular measuring tools (like the anemometer from our weather stations, for example). Newer tools, like Doppler radar, can measure wind speeds from a distance and be more accurate than older wind measuring instruments.

 

No. A tornado cannot last without warm rising air. When snow is on the ground, the air at groundlevel is cold, and therefore, there is no warm air that can rise. However, sometimes snow spins across the ground, which may look like a small tornado. These are called eddies, and they do not last more than a few seconds.

First, a few important facts about gravity:

1) Gravity is a force that pulls objects together.

2) Gravity is everywhere, even in space.

3) Gravity makes objects (even objects of different sizes, shapes, and weights) fall at the same rate.

You know that objects on the Earth, such as plants, people, animals, buildings, and more, are not floating because they are pressed against the ground. An object appears to float if it is not pressed up against its surroundings. In a spaceship in orbit, things look like they are floating because they are not pressed against the ship's surface. The gravity of the Earth is pulling the spaceship and the objects in the ship toward the Earth. Since the ship and the objects in it are falling at the same rate, the objects do not press against the ship's surface and appear to float.

 

Neil Armstrong was the first man to walk on the moon. The mission began on July 16, 1969, when the shuttle "Apollo 11" was launched with Neil Armstrong, Michael Collins and Edwin Aldrin, Jr. on board. On July 20, 1969, Neil Armstrong took the first step on the moon, and Edwin "Buzz" Aldrin, Jr. followed.

 

The earth is made up of seven VERY large, and over a dozen smaller, blocks of stone, which we call "plates". These plates move very slowly, so slowly that if you watch them, you wouldn't even be able to tell that they are moving at all. When these plates rub against or hit each other, the movement sometimes causes earthquakes.