The Earth on which we live is truly a beautiful place. It is filled with hundreds of colors, from the passing of the seasons and the changes from day and night, and is pulsating with life, lights and noise. But it is not the only place around. It is not even a very common place, because the universe in which it exists is mostly a cold, dark and empty void. The distances which separate us from other worlds don't make too much sense if measured in meters or kilometers, units which we use every day. So, in order to explore the space around us, we must pretend that we can move at the greatest speed known to man: the speed of light, which travels at about 300 000 kilometers per second. To get an idea of just how fast this is, a beam of light can travel around the Earth seven and half times in only one second, while the Concorde, the supersonic jet, would take no less than 252 hours to complete the same trip!
The Earth on which we live is truly a beautiful place. It is filled with hundreds of colors, from the passing of the seasons and the changes from day and night, and is pulsating with life, lights and noise. But it is not the only place around. It is not even a very common place, because the universe in which it exists is mostly a cold, dark and empty void. The distances which separate us from other worlds don't make too much sense if measured in meters or kilometers, units which we use every day. So, in order to explore the space around us, we must pretend that we can move at the greatest speed known to man: the speed of light, which travels at about 300 000 kilometers per second. To get an idea of just how fast this is, a beam of light can travel around the Earth seven and half times in only one second, while the Concorde, the supersonic jet, would take no less than 252 hours to complete the same trip!
