The influence of magnetic fields on the behavior of plasmas is dramatically illustrated by the coronal loop structure shown in this image acquired with the SOHO Extreme-ultraviolet Imaging Telescope (EIT). Magnetic field lines emerging from the photosphere (the Sun's visible "surface") and returning to it in a region of opposite magnetic polarity organize the hot (one million degree Kelvin) plasma of the corona into this loop structure on the Sun's eastern limb. This false-color image shows extreme ultraviolet emissions (195 angstroms) from highly ionized iron atoms (Fe XII) in the solar corona.

(Image courtesy of SOHO/EIT. SOHO is a project of international collaboration between ESA and NASA. More EIT images can be accessed at the SOHO Image Gallery.)