A Our Planet — the Earth

Our galaxy, the Milky Way, is part of the universe, which includes millions of other galaxies and their stars and planets. Compared to the rest of the universe, the Earth is very small. Compared to a person, on the other hand, the Earth is enormous. It has a diameter of 12,756 kilometers at the equator, and it has a mass of about 6 x 1024 kilograms. The Earth orbits the sun at a speed of about 29.79 kilometers per second.

From our perspective on Earth, the sun looks very small. This is because it is about 93 million miles away from us. The sun's diameter at its equator is about 100 times bigger than Earth's, and about a million Earths could fit inside the sun. The sun is inconceivably bigger. But without the sun, the Earth could not exist. In a sense, the Earth is a giant machine, full of moving parts and complex systems. All those systems need power, and that power comes from the sun.

The sun is an enormous nuclear power source – through complex reactions, it transforms hydrogen into helium, releasing light and heat. Because of these reactions, every square meter of our planet's surface gets about 342 watts of energy from the sun every year. The only way the Earth could generate more power than the sun would be if every three people had a power plant of their own. When this energy reaches the Earth, it provides power for a variety of reactions, cycles and systems. It drives the circulation of the atmosphere and the oceans. It makes food for plants, which many people and animals eat. Life on Earth could not exist without the sun, and the planet itself would not have developed without it.

As the Earth spins on its axis, parts of the planet are in the sun while others are in the shade. In other words, the sun appears to rise and set. The parts of the world that are in daylight get warmer while the parts that are dark gradually lose the heat they absorbed during the day. You can get a sense of how much the sun affects the Earth's temperature by standing outside on a partly cloudy day.

When the sun is behind a cloud, you feel noticeably cooler than when it is not. The surface of our planet absorbs this heat from the sun and emits it the same way that pavement continues to give off heat in the summer after the sun goes down. Our atmosphere does the same thing – it absorbs the heat that the ground emits and sends some of it back to the Earth.

The Earth's relationship with the sun also creates seasons. The Earth's axis tips a little – about 23.5 degrees. One hemisphere points toward the sun as the other points away. In this way the change of the temperature appears on Earth.

Ex. 5. Write out the constructions that will help you describe the size and physical position of a planet.

Ex. 6. Write out 1) the names of chemical elements and compounds, 2) main verbs that describe relationship between two planets.

Ex. 7. Compare planes of the solar system using comparative constructions. Don’t forget to mention their size, temperature, position towards the Sun, chemical elements that are found there. Use internet site http://nineplanets.org/ or any other source. Remember the names of the planets and mind their pronunciation: The Sun [sʌn], Mercury ['mɜːkj(ə)rɪˌ 'mɜːkjurɪ], Venus ['viːnəs] earth [ɜːθ], Mars [mɑːz], Jupiter ['ʤuːpɪtə], Saturn ['sætən], Uranus ['juər(ə)nəs], Neptune ['neptjuːn]