Earth Aurora Seen From ISS Orbit Near Indian Ocean

This gorgeous view of the aurora (above) was taken from the International Space Station as it crossed over the southern Indian Ocean on September 17, 2011. The sped-up movie spans the time period from 12:22 to 12:45 PM ET.

Credit: NASA

While aurora are often seen near the poles, this aurora appeared at lower latitudes due to a geomagnetic storm – the insertion of energy into Earth's magnetic environment called the magnetosphere – caused by a coronal mass ejection (CME) from the sun that erupted on September 14, 2011. The storm was a moderate one, rated with what's called a KP index of 6 on a scale that goes from 0 to 9, caused by just a glancing blow from the CME.

How are aurora generated?

As solar particles from an incoming CME move into Earth's magnetosphere they travel around to its back side -- or night side, since it is on the opposite side from the sun -- along the magnetic field lines. When these magnetic field lines reconnect in an area known as the magnetotail, energy is released and it sends the particles down onto Earth's poles, and sometimes even lower latitudes. As the particles bombard oxygen and nitrogen in the upper atmosphere, the atoms release a photon of light that we see as the beautiful colors of the aurora.