http://planet-today.ru/stati/interesno/item/43190-10-interesnykh-faktov-o-zemle-kotorye-vy-vozmozhno-ne-znali
Planet Earth, except that is home to humankind, still the only known place in the Universe where there is life. Every year people find out something new about the Earth, and even the oldest person in the world does not know all of its secrets and mysteries.We offered readers 10 interesting and little-known facts about the Blue planet.
1. The solid earth's crust relative. The planet's surface is actually made up of lithospheric plates that are in constant motion. Tectonic plates float on the surface contained in the Earth's core with magma. Exactly tectonics is responsible for earthquakes, volcanoes, ocean trenches and the subduction when one plate goes under another, resulting in a new earth. Tectonics and saves the Earth from greenhouse effect: organisms die and release carbon dioxide. If they were not absorbed by the ground, this would lead to a critical mass of carbon dioxide in the atmosphere. The earth would have warmed up and turned into hell.

2. The earth is actually not the ball. The name for the geometric shape of our planet is a scientific consensus. In fact, the Earth is shaped like a flattened sphere – compressed spheroid, or geoid. The planet is flattened towards the poles, and its radius in the area of "waist" by 21 km more. This, incidentally, explains another interesting fact: the greatest mountain peak in the world, with regard to the shape of the Earth is mount Everest (or Everest), as is commonly believed, and the inactive Chimborazo volcano in Ecuador.

3. The earth consists of iron, oxygen and silicon. If the planet is to share in its composition to look like this series will be as follows: 32.1 percent iron, 30.1% oxygen, 15.1 percent silicon and 13.9% magnesium. A large part of the iron is actually in the earth's core is 88%. With regard to the earth's crust, it is most oxygen – 47%.

4. 70% of the Earth's surface is not land. Is water. When someone first looked at the Earth from space, that's when it got its second name – the Blue planet. The remaining 30% is the so-called continental crust with an average thickness of 35-45 km, reaching up to 75 km under mountain ranges. Raising the Global sea level resulting from global warming and the melting of glaciers, is one of the main concerns of mankind. Maybe soon the percentage of land and water will have to be revised.

5. The terrestrial atmosphere extends to a distance of 10 thousand km, the atmosphere Consists of several layers: troposphere, stratosphere, mesosphere, thermosphere and ectosphere. At a distance of 50 km from the surface it is more dense, and the farther from it the density and pressure decrease. In fact, 75% of the earth's atmosphere is contained in the first 11 km from the planet's surface. The exosphere – the highest layer is the gateway into outer space, where no atmosphere at all. The exosphere mainly composed of hydrogen with a very low density of helium and of some heavy molecules of nitrogen, oxygen and carbon dioxide.

6. Molten "iron" core of the Earth creates a magnetic field. It's called the magnetosphere. In fact, the planet itself is a large magnet with poles. According to scientists, the magnetic field is generated in the molten outer core of the Earth, where heat creates convection motion of conducting materials, generating electric currents. Without a magnetosphere the planet would come to an end. The solar wind would hit the Earth directly, bringing down on it a huge amount of radiation. It is the depletion of the magnetic shield, according to one version, became a cause of death presumably fertile in the past of Mars.
7. The rotation of the Earth on its axis actually takes 24 hours. A full rotation of the planet takes 23 hours, 56 minutes and 4 seconds. This is a stellar day, as they are called astronomers. We can decide that in this case the day is actually 4 minutes shorter time it will accumulate, and after a few months, day will become night and night is day. But do not forget that the Earth revolves around the Sun. And the Sun itself is constantly shifting from its position by about one degree. If these two movements to fold, you get just 24 hours.
8. The duration of the earth year is not 365 days. This figure is in reality looks like this: 365,2564 days. These additional 0,2564 day lead to every four years a leap year which has 366 days. The exception to this rule is if the year is evenly divisible by 100 (1900, 2100, etc.) or if it is divisible by 400 (1600, 2000 etc.).

9. It is known that the Earth has one moon with the unpretentious name of the Moon. This is the only natural satellite of our planet. At least officially. Meanwhile, there are asteroids, which orbit similar to the orbit of the Earth – Cruithne (3753 Cruithne) and 2002 AA29. They belong to the class of asteroids, near-Earth (NEA). The diameter of the asteroid, Cruithne is 5 km away, and is sometimes called the "second moon". Despite the similarity of the orbits, Cruithne own unique path around the Sun. Diameter, 2002 AA29 is only 60 meters, and its orbit around the Earth has the form of horseshoe, every 95 years, bringing it closer to our planet. After about 600 years, he can become kazipoteka of Land, which, according to scientists, the asteroid makes it promising for research.

10. Earth the only known planet with life. So, despite the discovery of water and organic molecules on Mars, amino acids in space nebulae, the prospects of life under the icy crust of Jupiter's moon Europe or the Saturn Titan. But if life on other planets is, experiments and scientific work will certainly help to find her. For example, NASA announced the creation of the project NExSS. Its purpose is to process data sent by the space telescope "Kepler" and other similar devices, as well as learning exoplanets. But, in fact, the project is designed to search for extraterrestrial life. And yet, scientists wishing good luck searching, but we have to admit that the Earth is the only place suitable for life. And this is the main fact in its history.