Aurora Australis From SpaceEven for astronauts, this was a rare sight indeed: an aurora hovering over the southern Indian Ocean.Auroras occur when charged particles from the sun collide with Earth's upper atmosphere, causing atoms of oxygen and nitrogen to gain energy and then release it in the form of light.Auroras typically are visible only near Earth's Poles, where magnetic field lines channel charged particles toward the planet. But this aurora australis, photographed in May from the International Space Station, occurred during a geomagnetic storm, which can temporarily shift the planet's magnetic field—and hence its auroras—closer to the Equator.

Photograph courtesy NASA and NASA Earth Observatory