No one will doubt and ask the question, why the earth is round.After all, all of us are now fun to hear stories of how ancient people were a device and shape of the planet on which they live.Flat Earth, elephants, tortoise and the oceans ... Now since childhood everyone knows about the spherical shape of the Earth.But what is surprising to explain the reason for this can only units.The rest take the statement that "the earth is round," as an axiom.Fortunately, such people every year is getting smaller: natural curiosity and availability of information do the trick.
So, why the earth is round?To answer this question, we must remember what we know about the formation of the solar system.The working hypothesis, which is shared by the majority of astrophysicists, says that in the beginning of a rotating gas-dust cloud formed by the central star - the sun, and then the world.All particle rotating in circular orbits, the gravitational force acting, collecting them in a single celestial body.However, this does not explain why the earth is round, not any other form.The fact that one of the fundamental laws of the universe is the desire to absolutely all the material bodies to expend as little energy.In other words, everything in the universe tends to rest.The same is true of the spherical shape.Vectors of gravitational field propagate in all directions from the source (in this case - the center of the planet).Since they are nearly equal, the result is the formation of the spherical body, each surface point which is equidistant from a common center.Any change in this distance (for example, the appearance of the mountains) is a violation of equality and the variation of the gravitational field vector.After some time, inequality still persists, and the balance restored in some way (weathering, mechanical destruction).So, one of the main reasons why the earth is round - the action of gravitational forces.They are all the more pronounced, the more massive celestial body.In addition, the formation of the spherical shape is largely due to the liquid nature of the Earth's core.As is known, the shape of the ball is much easier to inject the gas and liquid.The Earth has a relatively thin layer of the cortex (the apparent contact surface) is an ocean of liquid red-hot magma.When volcanic eruptions, it spills out and freezes.There is a theory that in the very center of the planet is also a liquid core.The prerequisites for this assumption was the attempt to explain the emergence of the magnetic field generating currents of great strength in the center of the Earth.
By the way, if you look at the shape of large celestial bodies in the solar system, it becomes obvious that all the planets are spherical.Sometimes there is a slight violation of the form due to the flattening of the poles.His origin is obliged planet's rotation around its axis.But small bodies system - asteroids - can have virtually any shape.The reason for this lack of massiveness and as a result, the small gravitational forces.In addition, rotation, promotes the formation of spheres as either absent or insufficient.
sometimes on the forums can be found the question of what are the stars of the solar system.Until recently it was assumed that the star system is only one - is the sun.Increasingly, however, it sounded the assumption that our system - double.Besides the Sun is the second star, whose existence is proved only indirectly, but the name has already been given - nemesis.Because of its elongated orbit approach to the world it does not occur more than once every few thousand years.
