Under A Sunspot . ... Credit Copyright: MDI , SOHO Consortium , ESA , NASA Explanation: At the Sun's surface, sunspots are known to be dark, planet-sized regions of intense magnetic fields. ... Using observations from the Michelson Doppler Imager (MDI) instrument aboard the space-based SOHO observatory, astronomers have derived this premier picture of the flow of material just beneath a visible sunspot. ... NASA Web Site Statements, Warnings, and Disclaimers . NASA Official: Jay Norris. ...