Gravity has played an important role in the transformation of the universe, thanks to it it is possible for pieces of matter to join together to form planets, stars and moons, forming huge rotating galaxies and allowing planets to orbit around the stars.
According to Albert Einstein's approach, in 1915 gravity was an illusion and not a force of attraction. "Gravity is an effect of geometry. The earth disfigures the space-time of our context, in such a way that the space itself pushes us towards the ground ”. This apprehension of gravity belongs to Einstein's theory of general relativity. However, the classic definition of gravity is the one formulated by Isaac Newton where it is stated that "two bodies with mass, whatever they are, attract each other with force"
Gravity is an element of great importance when making astronomical observations, since in this sense there will always be a relevant force linked to each star that is observed. All the journey that the planets make in the universe has to do with this phenomenon, therefore it is a significant aspect in nature.
From the point of view of classical mechanics, gravity is a force that depends on the mass of the object in question. In this way, the greater the mass in a celestial body, the greater the attraction that it will make towards objects in its environment. However this interpretation of classical mechanics, which considers gravity as a force, has been in doubt by the theory of relativity.
It is very important to note that all matter has gravity, only that it is remarkable by the senses, in bodies of enormous sizes such as planets.
The characteristics of gravity are: it is capable of affecting the weight of objects on different planets, this means that every object in the universe (including planets) has gravity. The gravitational force is different on each planet, this will depend on its mass.
It affects the moon, since it will be influenced by the force of gravity of the planet earth. There are two forces that intervene to keep the earth rotating and keep the moon in orbit: centripetal and centrifugal forces; These two forces are what make it possible for the moon to be close without getting too close to the earth.
