Cosmos is hostile to living things. It is too cold or too hot in it, there is no air in it, it is empty and lifeless. Therefore, the appearance of the Earth, which has become home to humanity and an unimaginable number of other biological life forms, seems like a real miracle. There were many favorable factors that allowed life to arise: the optimal distance to the Sun, the appearance of a magnetic field, atmosphere, oceans and continents.
Currently, most of the area of planet Earth is covered by land and bodies of water suitable for life, only some areas with a harsh climate resemble desert space, however, even animals are found there. It is hard to imagine that once the Earth was a red-hot cloud of indefinite shape, consisting of cosmic particles and gas.
Birth of the World
According to the accepted theory, about 13.7 billion years ago a colossal explosion occurred, which sweeping through space an unimaginable amount of energy and matter. So the universe was born. At first, it was a continuous raging fire and was heated to a billion degrees. Particles of matter possessed too high energy and repelled from each other. But gradually the Universe was cooling down, atoms of helium, hydrogen and stardust dust began to appear, accumulating in nebulae, which became the forefathers of future stars and planets.
Land
Planet Earth appeared, like all celestial bodies, from a gas nebula, which began to shrink about 4.5 - 5 billion years ago. What caused the compression cannot be reliably said. The popular version is that according to which a powerful shock wave from a supernova that broke out in several light years helped the Earth to appear. The mass and area of planet Earth increased due to the gravitational attraction of comic particles and gases, which fell at great speed. The planet being born was a ball with a red-hot gut.
The advent of water and land
Bubbling gases, together with lava, burst out, and a primary atmosphere appeared. The whole Earth was covered with volcanoes and shrouded in gas clouds with a high water content, which condensed and fell in the form of rain, but again evaporated, touching the lava and the hot surface. The active volcanic period lasted two billion years and subsided about three billion years ago.
The planet was gradually cooling. The solidifying lava formed its land, and water vapor from the atmosphere and melted ice that got to the surface along with asteroids and comets turned into liquid. The area of planet Earth in those days was already commensurate with the present, but the first oceans were much smaller than modern ones. Volcanoes still erupted a billion years, but not so violently. The period of the geological formation of the Earth began. The planet was literally leveled by water and winds. Extinct volcanoes disappeared, plains appeared.
Supercontinent: Time of the Titans
According to reputable scientists, the continents do not stand still, but constantly drift. Moreover, every 500 years they converge into a single supercontinent. The last of these supercontinents existed 200 to 250 million years ago. He was given the name Pangea, which means “all the earth” from the Greek translation; his coast was washed by the single ocean of Pantalass. In total, the areas of Pantalassa and Pangea were equal to the total area of planet Earth.
Children of Pangea
About 170-200 million years ago, Pangea split into two parts for not clear reasons, which, in turn, were split into several tectonic plates. The continents and oceans were born in geological agony, the area of the entire land of planet Earth was redrawn. Evidence and eloquent traces of these grandiose processes are island arcs, recessed mountain ranges, oceanic depressions. The continents continue to converge, but the speed of their movement is meager compared to the size - only a few centimeters per year. According to rough estimates, they will again converge into the supercontinent after 250 million years.
solar system
But the presence of the atmosphere, the water shell, a sufficient amount of light and moderate temperatures is primarily due to the location of the Earth relative to the Sun. After all, life is possible only on one of the eight planets of the solar system. Depending on the structure, all the planets are divided into two groups and are distributed as follows according to the distance to the Sun.
Earth group planets:
- Mercury - 58 million kilometers to the Sun. The smallest planet in the system has a very rarefied atmosphere, which is why incredible temperature fluctuations are observed on the surface, which range from +430 ° to -190 ° .
- Venus - 108 million kilometers. In density, the atmosphere of this planet is ninety times greater than the Earth. Venus is a real greenhouse, its surface temperature is heated to 460 ° C, so water cannot remain in a liquid state, therefore, life is impossible.
- Earth - 149.5 million kilometers. Ideal living conditions. The mass and surface area of planet Earth is greater than each of the planets in the earth group.
- Mars is 228 million kilometers. The carbonic atmosphere of Mars is 500 to 800 times less dense than the atmosphere of Earth. The Martian surface is not able to maintain the temperature regime necessary for life. Mars is a very cold planet, at night frost prevails on its surface to -100 ° C.
Planets from the group of gas giants:
- Jupiter - 778 million kilometers. The largest planet in the solar system. Its mass is two and a half times greater than the total mass of the remaining seven planets, and the area is almost 122 times larger than the area of planet Earth. Jupiter predominantly consists of helium and hydrogen.
- Saturn - 1.43 billion kilometers. The density of this planet, which is known for its amazing rings, is less than the density of water.
- Uranus - 2.88 billion kilometers. The coldest planet in the system, the temperature on the surface of Uranus drops to -224 ° C.
- Neptune - 4.5 billion kilometers. The planet farthest from the Sun has an atmosphere consisting mainly of hydrogen and helium with methane impurities. Neptune, like Uranus, is very cold, the temperature on it drops below 200 ° C.
Analyzing this information, one can once again be amazed at the confluence of circumstances that made life possible on Earth. For a long time, scientists and science fiction allowed alien life on Venus and Mars, but studies of recent decades have shown that this is unlikely. On the neighbors of the Blue Planet, the climate is too harsh, the atmosphere density is inappropriate. There does not exist the ocean that generated the biosphere on Earth, and there is not enough powerful magnetic field to protect living things from the deadly radiation of the Sun.
Earth: important numbers
They are as follows:
- Diameter (average) - 6371 km.
- The equatorial circumference is 40,076 km.
- Volume - 1.08 * 1012 km 3 .
- Density (average) - 5518 kg / m 3 .
- Mass - 5.97 * 1021 tons.
- The speed of rotation around its own axis is 1675 km / h.
- The speed of rotation around the Sun is 107,000 km / h.
- A full revolution around its axis is 23 hours and 56 minutes.
- A revolution around the Sun - 365 days and 6 hours
What is the area of planet Earth: the distribution of water and land
The distribution of water and land on Earth has clearly developed in favor of water. Rivers, oceans, lakes and reservoirs cover 70.8% of the planet. However, the remaining land is enough for the lives of billions of people. In exact numbers, it looks like this:
- The total area of planet Earth (km2) is 510,000,000 km 2 .
- Land area - 149 million km 2 .
- The land area in the northern and southern hemispheres, respectively, is 100,000,000 km 2 and 49,000,000 km 2.
- The average land height above sea level is 860 m.
- The total area of water on planet Earth is 361,000,000 km 2 .
- The water area in the northern and southern hemispheres, respectively, is 155,000,000 km 2 and 206,000,000 km 2 .
- The average depth of the world's oceans is 3.7 km.
Interesting Facts
In fact, humanity lives on a poorly studied planet, because the ocean occupies more than 70% of its area, but the ocean depths are barely studied by 5%.
Scientists estimate that the approximate mass of water on Earth is more than 1.3 * 1018 tons, but the proportion of fresh water is only 3% of this enormous mass, with about 90% of it being in ice.
About 90% of the world's ice and 80% of fresh water is stored in the ice cap of Antarctica. This continent is the highest, its average height is 2.2 kilometers, which is two and a half times higher than the average height of Eurasia.
The area of Eurasia is about 55,000,000 km 2 , that is, 37% of the land area, but more than 5 billion people live in Eurasian states, which is 71% of the world's population.
The area of the Pacific Ocean is greater than the total area of all continents and islands and is 35% of the area of planet Earth.
Almost a third of the earth's surface is occupied by deserts.
Despite the high mountains and deep depressions, the surface of the Earth is very flat in comparison with its area. If the planet could be reduced to the size of a tennis ball, then the earth’s surface would be perceived by the palm as perfectly flat.