The diluted radiation plume from Japan's damaged nuclear reactors might brush the Aleutian Islands today and sweep into southern California by late Friday.
These NASA satellite photos from September 2010 and March 2011 show the contrast in the appearance of Japan's coastline, before and after the March 11 tsunami.
Arjun Makhijani studies shows how the U.S. could have low-carbon energy. He believes wind and solar energy would be cheaper and safer than nuclear power.