It is a celestial body that shines emitting its own light.
In general terms, a star is formed by a sphere of gas that is maintained at very high temperatures by virtue of the thermonuclear processes that develop inside. Our Sun is a typical medium-sized star.
Observing with the naked eye, on a serene night, we can distinguish around three thousand stars. However, already in one of the most gigantic stellar catalogs, the Palomar Sky Suzuey made with the 122 cm Schmidt telescope. from Monte Palomar, more than 800 million stars can be counted. The number of stars in the Universe is huge: only 100 billion are found in our Galaxy.
The stars are formed as a result of the condensation of large clouds of gases and dusts existing in the Universe. Events such as a collision between two of these clouds or variations in temperature and pressure inside one of them, induced by the activity of nearby stars, cause gravitational collapse phenomena: the particles of dust gas, then, fall towards a center of gravity.
A large cloud can be fragmented into many pieces, each of which collapses into its own center: in this case, each part of the cloud can give life to a star. As a result of the collapse, the temperature of the cloud gradually increases, reaching values of a tens of millions of degrees: at this point those nuclear reactions that give life to a star and provide energy throughout its existence are triggered.
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