Over the past many years, solar astronomers have argued about “solar tsunamis”; that is, large coronal shock waves on the Sun. Do they exist or are they figments of astronomers’ imaginations?

In 1959, Gail E. Moreton (1930-1982), a U.S. astronomer observing at the Lockheed Solar Observatory in Burbank, California, found what he described as a solar tsunami.

Using time-lapse photography on the chromosphere of the Sun, Moreton described hot plasma waves moving across the Sun’s surface at speeds of from 500 to 1,500 kilometers (310 to 930 miles) per second after being generated by solar flares.

He proposed that these solar tsunamis, also now called Moreton waves, occur when shock waves intersect the chromosphere of the Sun.

But, astronomers were not convinced. They were observed at various times over the next several decades.

According to the 11-24-2009 NASA media brief “Monster Waves on the Sun are Real,” astronomers saw this event recorded by Moreton but thought they were seeing something that wasn’t real—a figment of their imaginations.

The article states, “The scale of the thing was staggering. It rose up higher than Earth itself and rippled out from a central point in a circular pattern millions of kilometers in circumference. Skeptical observers suggested it might be a shadow of some kind—a trick of the eye—but surely not a real wave.”

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However, now, NASA has confirmed with its STEREO spacecraft that, indeed, this “monster wave” is real. Formally, this type of monster wave is called a fast-mode magnetohydrodynamical wave, or MHD wave for short.

The STEREO (short for Solar TErrestrial RElations Observatory) spacecraft is actually two spacecraft about ninety degrees apart from one another in their orbit about the Sun.

In February 2009, they observed Sunspot 11012 erupt and send a billion-ton cloud of gas, what is called a CME, into space. This blast generated a tsunami that sped across the surface of the Sun.

And, the STEREO spacecraft recorded this action.

Joe Gurman, of the Solar Physics Laboratory at the NASA Goddard Space Flight Center in Greenbelt, Maryland, stated, "Now we know. Solar tsunamis are real."

A video of the solar tsunami observed by STEREO is found on the NASA website mentioned earlier.

What STEREO recorded was a tsunami that was about 100,000 kilometers (60,000 miles) in height. It had a speed of about 250 kilometers per second (560,000 miles per hour). And, it had as much energy as 2,400 megatons of TNT.

See an animation of a solar tsunami at Space.com.

Learn more about these monster solar tsunamis at the February 8, 2002 Montana State University article “Moreton waves and coronal waves.”