Total solar eclipse 2017: When is it, why is it happening and how can I see it in the UK?

What's happening? On Monday, August 21, 2017, all of North America will witness an eclipse of the sun for the first time in 99 years, where the Moon will pass in front of the Sun casting darkness across swathes of the Earth's surface. Dubbed the Great American Eclipse, the moment will see the Sun, the Moon and the Earth become perfectly aligned in a once-in-a-lifetime celestial spectacle seen from the Pacific Ocean to the Atlantic Ocean. Although we won't see a perf