In much of the country this week, the greatest show is not on earth, but above it: spectacular displays from the aurora borealis, or northern lights.
The northern lights occur when charged particles emitted by the sun strike the Earth's atmosphere. The resulting visual displays can be beautiful and dramatic. Stargazers in many parts of the continental United States and Canada have been treated to sightings of red, green and white lights across the night sky.
NPR's Robert Siegel speaks with Anthony Arrigo, a software engineer and amateur astronomer in Park City, Utah, who's been writing about the aurora borealis on his Web site.