A total eclipse of the Sun is a spectacular cosmic event that can even be life changing. The 21st August 2017 sees one of the most accessible eclipses for years, an all-American eclipse crossing the United States for more than two thousand miles from northwest to southeast. And yet throughout the centuries, the sight of a total eclipse - seeing the Sun totally blacked out by the moon – has often caused fear and turmoil. Joining Rajan Datar to find out more about the history of eclipses and what they reveal about the workings of the Sun is the NASA astrophysicist Lika Guhathakurta, the eclipse chaser and psychologist Kate Russo, and Marek Kukula, public astronomer at the Royal Observatory in Greenwich in London.

Photo: A total eclipse of the Sun (BBC)