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Transcript
Stars
A ‘Star’ is a large celestial body composed of gravitationally contained hot gases
emitting electromagnetic radiation, especially light, as a result of nuclear reactions
inside the star.
The sun is a star. With the exception of the sun, stars appear to be fixed, maintaining
the same pattern in the skies year after year. However, stars are actually in rapid
motion, but their distances are so great that their relative changes in position become
apparent only over the centuries.
The number of stars visible to the naked eye from earth has been estimated to total
8000, of which 4000 are visible from the northern hemisphere and 4000 from the
southern hemisphere. At any one time in either hemisphere, only about 2000 stars are
visible. The other 2000 are located in the daytime sky and are obscured by the much
brighter light of the sun.
Astronomers have calculated that the stars in the Milky Way, number in the hundreds
of billions. The Milky Way, in turn, is only one of several hundred million such
galaxies within the viewing range of the larger modern telescopes. The individual
stars visible in the sky are simply those that lie closest to the solar system in the Milky
Way.
The star nearest to our solar system is the triple star ‘Proxima Centauri’, which is
about 40 trillion km (about 25 trillion mi) from earth.