Gravity is the force of attraction between objects.
In the universe all matter moves because of this and other forces.
The severity depends on the mass of the objects and the distance that separates them. How much more mass they have and are closer, greater is the force. When separate double, the force is reduced to a quarter.
Gravity acts as if all the mass of a body to focus on a single point, the center of gravity. The spherical area around a body acts where its gravity is the gravitational field.
The law of universal gravitation was formulated by British physicist Isaac Newton in the year 1684.
If we stopped two bodies with mass and at rest, unless you act any other force except in their attraction, inevitably, they would collide. But in the universe there are many "gravities", they act other forces and bodies are in motion.
A gravitational collapse is when a body becomes smaller as a result of its own gravity, for example, a cloud of gas to form a star, or a star to form a black hole. Atoms are broken and the building collapses.
Atoms are empty boxes where a force maintains the structure. But if gravity exceeds this force, the central structure will not hold and matter starts a chain reaction.
The density increases (the body is small without losing mass), the gravitational field intensifies and the collapse occurs.
Fundamental forces of the universeThere are four fundamental forces that determine all forms of interaction of matter:
-strong nuclear interactions,
-weak nuclear interactions,
Gravity is the weakest of the four and the only one that only works in one direction. The scientists speculate about whether the supplementary.
The universe is in motion
Stars, galaxies and the universe move. Another thing is to detect the movement of some bodies, especially in the most distant.
The movement of many objects in the universe has been measured. So we know that, to move a distance apparent equal to the diameter of the Moon, the star nearest Alpha Centaur, need 506 years. Arthur need 815; Syrian, 1.410; Altair, 2.830; Capella, 4270 and Fomalhaut, more than 5,000.
Orbit called the trajectory of an object which revolves around another. The orbital period is the time that the object takes to complete an orbit. It seems that all objects in space, orbiting around others with more mass.