We're used to lightning that strikes from cloud to ground, or within the clouds themselves. But in the last decade, a new form of lightning has been identified that goes from the tops of thunderstorms upward, into space. Two variations of this exotic lightning are known as red sprites and blue jets.

Red sprites are huge but dim flashes of red light that appear above some large thunderstorms. They were first observed in 1989, and since then hundreds have been photographed from the space shuttle. They can reach more than 50 miles up into the atmospheric layer called the mesosphere. Blue jets appear lower, between 15 and 30 miles up, in the stratosphere. They appear to come directly from the tops of thunderstorms and shoot upward in narrow cones.

The exact mechanism that drives sprites and jets is still largely unknown, but they seem to be common enough that they're likely an essential part of the earth's global electrical system.