In 1609, Galileo Galilei pointed his newly invented telescope towards the heavens and became the first of all men to see that there were other worlds beyond the Earth. Years later, Nicholas Copernicus paved the way for the modern picture of the universe. He came up with a theory of the solar system in which the sun is the central body and other planets revolved around it. A whole new science was born. As a result, many scientists focused on the planets making great discoveries. Astronomy ceased to belong to the theologians and became an extension of geography. Only a few decades after the first telescope was invented, a whole literature of space travel had emerged, mixing fiction with newly acquired astronomical knowledge (Man and Space 9-10).
Today, there is no one who can predict just how fast humans will spread out across the solar system or just how far we shall be able to explore it. New technologies such as nuclear propulsion will make it easier to access other planets. Scientists predict that a century from now, the planet Pluto will seem closer to our grandchildren than the Earth's poles did to our grandparents. There is no doubt that the powers that are now coming into our hands will be enough to reshape this solar system like we have already reshaped the Earth (Man and Space 153). .
In order to avoid extinction of the human race from cosmic catastrophes, mankind must use scientific knowledge to protect ourselves. For humans to sustain long-term survival, animal and plant and human populations must eventually be spread out to other planets or space habitats. If we do not disperse life to other planets and our planet is bombarded by giant cosmic catastrophes like those of Comet Shoemaker-Levy 9 that slammed into Jupiter in July 1994, the probability of human survival would be very minute. The life on any planet will, however, eventually become extinct, if for no other reason than the death of its own sun.