Tsunamis on the Earth can be terrifying enough - a wall of ocean water surges inland after being set loose by an undersea earthquake, and crushes all in its path. Hundreds of thousands died in the December 2004 tsunami (astonishing video below) that originated in Indonesia.

But imagine a tsunami of hot plasma that is 62,000 miles high, travels at half a million miles per hour and packs the power of 2,400 megatons of TNT. That's what scientists have discovered on the sun.

Solar tsunamis are harmless to life on Earth. But understanding them - and being able to spot them - may help solar scientists better predict and anticipate the effects of coronal mass ejections and other eruptions on the sun that can and do affect human communications, power grids, satellites and other systems on and around the Earth.

NASA's twin STEREO spacecraft recorded a solar tsunami in February of this year, and produced two movies of the event, taken from two different angles. The discovery allowed scientists to confirm the theory that had been proposed in 1997 when another spacecraft, called SOHO, spotted what looked like a solar tsunami, but which some thought might be something else.

You can read more about this phenomenon here.