Solar activity reconstructed (IMAGE) ETH Zurich Caption Solar activity over the last 1000 years (blue, with error interval in white), sunspot records (red curve) going back less than 400 years. The background shows a typical eleven-?year cycle of the sun. Credit ETH Zürich Usage Restrictions The rights to the images always remain with the person referred to as the copyright holder for them. Images published on ETH News may be used by other media and online portals only if ETH Zurich is specifically mentioned as the copyright holder and only in connection with the relevant ETH News article. Further distribution of images - for example, via download links - is permitted only with the approval of the editorial team. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.