Scientists spend years preparing for the two-minute window of a total solar eclipse.
If you've ever wondered why you can look at a solar eclipse and why it can harm your eyes, the answer is in the sun's rays.
For centuries, scientists have known when and where eclipses will be visible. They pack their bags, head for the line of totality and hope for the best – which doesn't always happen.
An astronomer explains how and why – and when – eclipses happen, what we can learn from them, and what they would look like if you were standing on the moon.