Astronomers of the eighteenth century spent months travelling around the globe to time the transit of Venus in order to calculate the distance to the Sun. Three centuries later you only need to travel as far as the app store to download VenusTransit onto your smart phone to take these measurements yourself.
The app will help you practise timing the contact points of Venus with the solar disc before the event. On the day, just tap your phone at the exact time and your recordings will be sent to a global database, using GPS to record your location. The data will be accessible online after the event for comparison with other VenusTransit app users, and will be used to measure the Sun’s distance in a digital recreation of the historical exploration efforts!