In Jules Verne's 1865 novel From the Earth to the Moon, men went to the Moon in a bullet-shaped spacecraft fired from an enormous gun. But in reality, the high acceleration caused by such an explosion would crush a human being. The only practical way for humans to reach space is to do it gradually--to accelerate slowly over a very long path. This is exactly what a rocket does. It provides slow but steady acceleration over a distance of more than 1,000 kilometers (600 miles).