Planet Earth, besides being home to humanity, is also the only known place in the universe where there is life. Every year people learn something new about the Earth, and even the oldest person in the world does not know all its secrets and mysteries. Universe Today magazine offered readers 10 interesting and little-known facts about the Blue Planet.
1. The crustal solid is relative. The planet's surface is actually composed of lithospheric plates in constant motion. Tectonic plates float on the surface of magma contained in the Earth's core. It is tectonics that is responsible for earthquakes, volcanic eruptions, ocean trenches and subduction proper, when one plate goes under another, resulting in the formation of a new earth solid. And tectonics also saves the Earth from the greenhouse effect: organisms die and release carbon dioxide. If they were not absorbed by the earth, this would lead to a critical mass of carbon dioxide in the atmosphere. The earth would warm up and turn into hell.
2. The earth is not really a ball. This name for the geometrical shape of our planet is a scientific consensus. In reality, the Earth has the shape of an oblate ball - a compressed spheroid, or geoid. The planet is flattened in the direction of the poles, and its radius at the "waist" is 21 km larger. This, incidentally, explains another interesting fact: the greatest mountain peak in the world, given the shape of the Earth, is not Chomolungma (or Everest), as is commonly believed, but the inactive volcano Chimborazo in Ecuador.
3. The earth is composed of iron, oxygen and silicon. If the planet is divided according to its composition, this row will look like this: 32.1% iron, 30.1% oxygen, 15.1% silicon and 13.9% magnesium. Moreover, most of the iron is actually in the earth's core - 88%. As for the earth's crust, it contains the most oxygen - 47%.
4. 70% of the Earth's surface is not land. This is water. When people first looked at Earth from space, it was then that it got its middle name - the Blue Planet. The remaining 30% is occupied by the so-called continental crust with an average thickness of 35–45 km, reaching up to 75 km under the mountain ranges. The rise in the level of the World Ocean, which occurs as a result of global warming and the melting of glaciers, is one of the main causes of concern for humanity. It may soon be necessary to revise the percentage of land and water.
5. The Earth's atmosphere extends to a distance of 10 thousand km. The atmosphere consists of several layers: the troposphere, stratosphere, mesosphere, thermosphere and exosphere. At a distance of up to 50 km from the surface, it is denser, and with distance 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" to outer space, where there is no atmosphere at all. The exosphere is mainly composed of very low density hydrogen, helium, and a number of heavy molecules such as nitrogen, oxygen and carbon dioxide.
6. The molten "iron" core of the Earth creates a magnetic field. It is called the magnetosphere. In fact, the planet itself is a large magnet with poles. According to scientists, a magnetic field is generated in the molten outer core of the Earth, where heat creates convective motions of conductive materials that generate electric currents. Without the magnetosphere, the planet would have come to an end. The solar wind would hit the Earth directly, unleashing a massive amount of radiation on it. It is the depletion of the magnetic shield, according to one of the versions, that caused the death of the supposedly fertile Mars in the past.
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7. The rotation of the Earth on its axis does not actually take 24 hours. A complete revolution of the planet takes 23 hours, 56 minutes and 4 seconds. This is a sidereal day, as astronomers call them. We can decide that in this case the day is actually 4 minutes shorter, this time will accumulate, and after a few months the day will become night, and night - 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 you add these two movements, you get exactly 24 hours.
8. The duration of the earth year is not at all 365 days. This figure in reality looks like this: 365.2564 days. These additional 0.2564 days result in a leap year of 366 days every four years. An exception to this rule is if the year is divisible by 100 (1900, 2100, etc.), and if it is not a multiple of 400 (1600, 2000, etc.).
9. It is known that the Earth has one moon with an unpretentious name Moon. It is the only satellite of our planet. At least officially. Meanwhile, there are asteroids whose orbit is similar to that of the Earth - Cruithne (3753 Cruithne) and 2002 AA29. They belong to the class of near-Earth asteroids (NEAs). The asteroid Cruithney is 5 km in diameter and is sometimes referred to as the "second moon". Despite the similarity of the orbits, Cruithney has its own unique path around the Sun. 2002 AA29 is only 60 m in diameter and orbits the Earth in a horseshoe shape, bringing it closer to our planet every 95 years. In about 600 years, it may become a quasi-satellite of the Earth, which, according to scientists, makes the asteroid promising for research.
10. Earth is the only planet known today with life. This is so, despite the discovery of water and organic molecules on Mars, amino acids in cosmic nebulae, the prospects for the existence of life under the icy crust of Jupiter's moon Europa or on Saturnian Titan. But if there is life on other planets, experiments and scientific work will certainly help to find it. For example, NASA announced the creation of the NExSS project. Its purpose is to process data sent by the Kepler space telescope and other similar vehicles, as well as to study exoplanets. But, in fact, the project is designed to search for extraterrestrial life. And yet, wishing scientists good luck in their search, while we have to admit that the Earth is the only place suitable for life. And this is the most important fact in her history.