This ominous, dark shape sprawling across the face of the active Sun is a coronal hole [ http://www.spacescience.com/headlines/y2000/ast23feb_2.htm ] -- a low density region extending above the surface [ http://antwrp.gsfc.nasa.gov/apod/ap001115.html ] where the solar magnetic field opens freely into interplanetary space [ http://www.spaceweather.com/ ]. Studied extensively from space [ http://vestige.lmsal.com/TRACE/POD/Sunscapes.html ] since the 1960s in ultraviolet [ http://antwrp.gsfc.nasa.gov/apod/ap010929.html ] and x-ray light [ http://www.lmsal.com/YPOP/homepage.html ], coronal holes are known to be the source of the high-speed solar wind [ http://antwrp.gsfc.nasa.gov/apod/ap000318.html ], atoms and electrons which flow [ http://cfa-www.harvard.edu/~scranmer/SURF/ surf_bkgd.html ] outward along the open magnetic field [ http://solar.physics.montana.edu/YPOP/Spotlight/ Magnetic/ ] lines. During periods of low activity, coronal holes [ http://www.solar.isas.ac.jp/english/hole.html ] typically cover regions just above the Sun's poles. But this coronal hole [ http://sohowww.nascom.nasa.gov/pickoftheweek/old/15jan2002/ index.html ], one of the largest seen so far in the current solar activity cycle [ http://science.nasa.gov/headlines/y2002/18jan_solarback.htm ], extends from the south pole (bottom) well into northern hemisphere. Coronal holes [ http://solar.physics.montana.edu/nuggets/2001/011116/ 011116.html ] like this one may last for a few solar rotations before the magnetic fields shift and change configurations. Shown in false-color, this picture of the Sun on January 8th was made in extreme ultraviolet light by the EIT [ http://umbra.nascom.nasa.gov/eit/EIT.html#WHAT_EIT ] instrument on board the space-based SOHO observatory.