]NASA's Solar Dynamics Observatory (SDO), best known for
cutting-edge images of the sun, has made a discovery right here
on Earth. "It's a new form of ice halo," says atmospheric optics
expert Les Cowley of England. "We saw it for the first time at
the launch of SDO--and it is teaching us new things about how
shock waves interact with clouds." Ice halos are rings and arcs
of light that appear in the sky when sunlight shines through ice
crystals in the air. A familiar example is the sundoga rainbow-
colored splash often seen to the left or right of the morning
sun. Sundogs are formed by plate-shaped ice crystals drifting
down from the sky like leaves fluttering from trees. Last year,
SDO destroyed a sundogand that's how the new halo was
discovered. SDO lifted off from Cape Canaveral on Feb. 11,
2010one year ago today. It was a beautiful morning with only a
handful of wispy cirrus clouds crisscrossing the wintry-blue
sky. As the countdown timer ticked to zero, a sundog formed over
the launch pad. "When the rocke