Nature's Third Cycle

The cycle of day and night and the cycle of seasons are two familiar natural cycles around which many human activities are organized. But is there a third natural cycle of importance for us humans? On 13 March 1989, six million people in Canada went without electricity for many hours: a large explosion on the sun was discovered as the cause of this blackout. Such explosions occur above sunspots, dark features on the surface of the Sun that have been observed through telescopes since the time of Galileo. The number of sunspots has been found to wax and wane over a period of 11 years. Although this cycle was discovered less than two centuries ago, it is becoming increasingly important for us as human society becomes more dependent on technology. For nearly a century after its discovery, the cause of the sunspot cycle remained completely shrouded in mystery. The 1908 discovery of strong magnetic fields in sunspots made it clear that the 11-year cycle is the magnetic cycle of the sun. It is only during the last few decades that major developments in plasma physics have at last given us the clue to the origins of the cycle and how the large explosions affecting the earth arise.Nature's Third Cycle discusses the fascinating science behind the sunspot cycle, and gives an insider's perspective of this cutting-edge scientific research from one of the leaders of the field.

Arnab Rai Choudhuri is a Professor of Physics at the Indian Institute of Science. He received his PhD in 1985 from the University of Chicago under the supervision of Eugene Parker, usually regarded as the most influential solar physicist of our time. Choudhuri has carried on theoretical research on the formation of sunspots and the 11-year sunspot cycle. He was one of the originators of the flux transport dynamo model, the currently favoured theoretical model of the 11-year sunspot cycle. He is the author of two advanced textbooks, The Physics of Fluids and Plasmas (CUP, 1998) and Astrophysics for Physicists (CUP, 2010), used in many universities around the world.

"The scientific detective work investigating the structure and activity of the Sun is a mystery story that should not be missed. 'Nature's Third Cycle' is an outstanding account of the case, carrying the reader from the first discoveries through the numerous stages of the puzzle to the latest results on the magnetic cycle of activity." - Eugene Parker, University of Chicago

"This is a highly engaging and informative account of the fascinating discoveries that have been made about the nature of the Sun and its spots, enlivened by the often colourful characters who have striven to understand it, and woven together with the author's personal story which is honestly told and frequently moving." - Stephen Blundell, University of Oxford

"No astrophysical process other than the solar cycle has left massive footprints on our living environment. Arnab tells many stories about eminent astrophysicists, their personal lives and their ceaseless striving for new understanding and scientific truth. The tales about his supervisor, the giant Eugene Parker and his own scientific career are so vivid and engaging with his own style - frank, honest, enthusiastic and ready for scientific debate." - Jingxiu Wang, National Astronomical Observations, Chinese Academy of Science

"Our Sun influences the climate and space environment of the Earth in profound ways. In his wonderful popular book on science, Choudhuri describes the history and current understanding of the sunspot cycle, and skilfully weaves in the tale of his own career with its hopes and fears, difficulties and joys." - Eric Priest, St Andrews University

"... makes compulsive reading. Arnab Rai Choudhuri has succeeded in producing an interesting and instructive book. He writes in an engaging style and his own personal tale will carry readers through the scientific details." Nigel Weiss, University of Cambridge