In March 2015 there was an eclipse of the Sun. Those who saw the total eclipse from the North Atlantic witnessed one of the most awesome sights imaginable. From more southerly locations we saw a partial eclipse, and in Cardiff we were joined by over 1000 people on the steps of the National Museum of Wales.

But eclipses aren’t just a pretty sight, and they can be used for scientific purposes. As well as showing us the outer atmosphere of the Sun, they are also able to tell us about the fabric of the Universe itself. This month, I spoke to Mark Hannam, a researcher here in Cardiff, about what eclipses have taught us about gravity, and what we’re still learning today. You can also read Mark’s blog post about some of the concepts involved.

Originally broadcast (in edited form) on 26th March 2015 as part of Pythagoras’ Trousers on Radio Cardiff.