The distant galaxies we have seen are moving away from earth by the red shift the law that describes its expansion is Hubble's law. It is regarded as the main observational basis on enlargement of the world. and imitation to acquire the supportive evidence over big bang model. It states that galaxies are becoming extinct at a speed that is proportional to their distance.
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Changes to the classification system have meant that the classification of some species of organisms has changed too. The system had to be changed to incorporate this new group or organisms.
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