Irene González Hernández
National Solar Observatory
September 7th Flare of active region 808
Until recently, the ever-changing magnetic activity on the solar surface could only be studied when the Sun faced the Earth.
Helioseismic holography, developed by Lindsey and Braun(1997,ApJ), made it possible to map the magnetic regions on the non-visible or farside of the Sun before they appear in the front side.
Click here to see maps of active region AR 10808 by applying phase-sensitive holography to GONG images before it appeared on the front side Sept. the 7th with a spectacular solar flare.