Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.
In the Briefings section of 22 September(p. 1332), the creditfor the x-ray image of the sun should have included EberhardSpiller of IBM's Watson Research Center.