A tsunami on the Sun's surface (c) Nasa
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Speedy tsunami seen on Sun surface

Two Earth-orbiting satellites have caught sight of speeding "tsunami" on the surface of the Sun after an event called a coronal mass ejection (CME).

These waves of heightened magnetic field and hot, ionised gas race across the Sun at about 400km per second.

The chance sighting, to be published in Solar Physics, allowed researchers to measure the magnetic field in "quiet" areas away from the CME.

Understanding this field may help predict how CMEs will affect the Earth.

In this "false colour" clip of ultraviolet light on the Sun, purple corresponds to the highest temperatures.

After the CME, the green, lower-temperature wave - at about 1,000,000C - can be seen spreading across the Sun's surface.

Footage courtesy of Nasa

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