The universe may be a big, big place. But how big? and the way can we know? Throughout history, humans have used a spread of techniques and methods to assist them answer the questions 'How far?' and 'How big?' Generations of explorers have looked deeper and deeper into the vast expanse of the universe. and therefore the journey continues today, as new methods are used, and new discoveries are made. (To learn more about distance, visit How Big is Our Universe.) In the third century B.C., Aristarchus of Samos asked the question 'How distant is that the Moon?' He was ready to measure the space by watching the shadow of the world on the Moon during a eclipse . It was Halley , famous for predicting the return of the comet that bears his name, who three centuries ago found how to live the space to the Sun and to the earth Venus. He knew that the earth Venus would very rarely, every 121 years, pass directly between the world and therefore the Sun. The apparent