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The Earth and the Solar System

We, humans, live on the Earth. And our planet Earth is surrounded by space. The sky is what we see of space. There are billions of stars and probobly billions of other planets moving through space. Our planet is moving through space too. We live on the surface of our planet Earth. Gravity keeps us here on the Earth. Gravity is an invisible force that pulls things and people toward the center of the Earth. All the other planets, stars and moons have gravity too. Without gravity we would float away into space. The Sun lights up the Earth. The Earth turns around each day. The half of the Earth turned away from the Sun is dark. On that half of the Earth it is night. The half of the Earth turned toward the Sun is light. On that half it is daytime. We, humans beings, have always wanted to know what is out in space. We have created telescopes and spaceships to find out. Astronomers use giant telescopes to study the moon, stars and planets. Astronauts travel in spaceships explore parts of space that are too far away for people to visit. The Sun is really a star. Stars are fiery balls of burning gas. We cannot go to the Sun because it is much too hot. The Sun is a million times bigger than the Earth. It's much closer to the Earth than the other stars. That is why the Sun looks so bright to us. The Sun gives light and heat. We, human beings, would not be alive if there were on sun. Plants and animals could not live either. The Moon is our nearest neighbor in space. The Moon is smaller than the Earth. It moves around the Earth in a path, called an orbit. Astronauts have visited the Moon. A spaceship takes a half days to go from the Earth to the Moon. Mercury is a planet closed to the Sun. It is so hot, that nothing can live here. The spaceship sent back pictures of the surface of Mercury. It has rocks and craters like the Moon's. Venus is the second planet from the Sun. It is the closest planet to the Earth and about the same size as the Earth. You can easily see Venus in the sky without a telescope. But even the strongest telescope cannot see the surface as it is cavered by thick clouds. These cloud are made of acid instead of water. Mars is about half as big as the Earth. You can also see Mars in the sky without a telescope. For many ears people have imagine that there are intelligent humanlike beings on Mars, but there is no breathable are on Mars, so Earthlike beings cannot live there. Saturn is the second largest planet. It has at list 20 Moons. Jupiter is the biggest planet in our solar system. The solar system is a very small part of the Milky Way galaxy, this galaxy may have 2 hundred billions stars.

Healthy Food

All food is made up of nutrients which our bodies use. There are different kinds of nutrients: carbohydrates, proteins, fats, vitamins and minerals. Different kinds of food contain different nutrients.

Before we cut down on fat, sugar and salt, we have to know a bit more about the kind of food these things might be in. The biggest problem comes when these things are hidden in other foods: biscuits, crisps, sausages, meat pies, soft drinks and so on. The best way is to get into the habit of checking the ingredients and nutritional value on the sides of packets although this isn't always easy to do. Another thing to know is, for example, that we do need fat to live, it's an essential part of our diet and physically we couldn't exist without it. But we all know that to eat much fat is bad for our health. The matter is that there are different kinds of fat. There are fats that are good for us and fats that are bad for us. Eating less of the bad ones and more of the good ones can actually help us to live longer! Bad fats are the saturated fats, found in animal productions, like red meat, butter and cheese.

Friendly fats are the unprocessed fats found naturally in foods like nuts and seeds, olives, avocados and oily fish, including tuna. One more thing to know is that when food is cooked, its structure changes. It can change the vitamin and nutrient contents of food. More and more people feel strongly about the way, their food is produced. Nowadays so much of the basic food we eat meat, fish, fruit and vegetables is grown using chemicals and additives.

Although fertilizers and pesticides have greatly increased the quantity of food and helped to improve its appearance, there is a growing concern about the effects of these chemicals in the food chain. This concern has led to a growth in the demand for organically grown products. Today there is another problem. It is modified food, which is cheaper that ordinary one. There is a rumour that such food can cause cancer and other problems. Nobody knows, either it is just an imagined fear or a real problem. This problem could be solved and examined, but it will take some time. The food we eat, depends on lots of things. Taste is a big factor. Culture, religion and health also play a part in what food we eat. Advertising and social factors also have a big influence.

Income is also an important factor. That is why not surprisingly, money, rather than a lack of knowledge about how to eat well, is at the heart of the problem. Finally, there are three main messages to follow for healthy eating: First, we should eat less fat, particularly saturated fat. Secondly, we are to cut down on sugar and salt. Thirdly, we must eat more fresh fruit and vegetables.

Date: 2015-12-11; view: 60

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