Three views of the 2004 Venus transit. Credit: NASA

In a matter of hours, lucky observers with clear skies will be able to watch Venus pass in front of the Sun. Transits of Venus are rare this is the last one until 2117 but that s not the only reason you should find a way to watch it. This astronomical event is historically very significant. Since the 17th century astronomers have used Venus transits to better understand the Universe and our place within in, and the upcoming transit doesn t break this centuries-old tradition.