(Astronaut Ron Garan tweeted this photo by fellow spaceflyer Mike Fossum (@astro_aggie) on October 5, 2011, showing auroral glow over Earth. He wrote: “@Astro_Aggie is changing the way us earthlings view our planet. Great snap Mike! #ISS #NASA.” CREDIT: Ron Garan/Mike Fossum )

“Despite the presence of a brilliant nearly-full moon, skywatchers should pay attention to the northern sky tonight. If nature is in a showoff mood, for the second time in less than three weeks, a nice display of the Aurora Borealis — popularly known as the northern lights — may flare up.”

“The potentially dazzling northern lights display is possible because of solar flares, which are tremendous explosions on the surface of the sun. In a matter of just a few minutes they heat material to many millions of degrees and release as much energy as a billion megatons of TNT.”