Solar-powered flight and the Crazy Horse Memorial

Max Pearson presents a collection of the week's Witness History episodes.This week, we hear about the first solar-powered flight around the world, and discuss other moments in the history of solar power with Prof Laura Herz, Professor of Physics at the University of Oxford, in the UK.Plus, the start of the largest mountain carving in the world in honour of Native American warrior Crazy Horse, Mexico's 'little old lady killer' and the birth of the 'African Oscars', FESPACO.Finally, when American football came to Europe and how a Peruvian instrument, the cajon, revolutionised flamenco.Contributors: Bertrand Piccard - one of the pilots of Solar Impulse 2. Prof Laura Herz, Professor of Physics at the University of Oxford. Monique Ziolkowski - daughter of the sculptor who started the Crazy Horse Memorial. Dr Feggy Ostrosky - neuropsychologist who worked with Juana Barraza. Alimata Salembéré - president of the first organising committee of the Pan African Film and Television Festival. Oliver Luck - former president of NFL Europe. Rubem Dantas - percussionist who helped introduce the cajon into flamenco.(Photo: Solar Impulse 2 flies over the Golden Gate bridge in San Francisco in 2016. Credit: Jean Revillard via Getty Images)