How far away is the Sun?

Chapter 1Light takes timeYou know your street and your city. But how far is it to the next big house in the neighborhood — the Sun? Nobody has ever been there, and nobody has sent a tape measure. And yet we know its average distance to within a few meters.0 of 1 levels

Chapter 2Measuring the skyNobody has walked to the Sun or a star. So how do we know how far they are? With a thumb, a planet crossing the Sun and a lot of patience.0 of 3 levels

1. Level 1Light takes its time
2. READYLevel 2Measuring with your thumb
3. READYLevel 3A light-year is a distance
4. READYLevel 4Closer means faster