Eclipses have been aiding scientists throughout history, from helping measure the width of the Atlantic ocean and verifying Einstein's theory of general relativity, to allowing NASA to attempt a thermal mapping of Mercury. Subscribe for regular science videos: http://bit.ly/RiSubscRibe For the first time in nearly 100 years, a total solar eclipse will be visible across the entire contiguous United States. Professor Frank Close, particle physicist, former Christmas Lecturer and eclipse enthusiast takes us on a journey through history to uncover how these celestial events have helped us understand more about our planet, the solar system and the universe beyond. The Ri is on Twitter: http://twitter.com/ri_science and Facebook: http://www.facebook.com/royalinstitution and Tumblr: http://ri-science.tumblr.com/ Our editorial policy: http://www.rigb.org/home/editorial-policy Subscribe for the latest science videos: http://bit.ly/RiNewsletter