Solar Tornadoes Turn Out To Be Not Quite What They Seem

See that black-ish plume of plasma? That's a solar tornado - except that it isn't. SDO/NASA

The proclivities of stars will always serve to make us seem incredibly, fantastically small – and solar tornadoes are no exception to this. These vast, twisting structures, seen on the surface of our very own local star, are often large enough to consume multiple Earths, and as observed by NASA’s Solar Dynamics Observatory (SDO) satellite, they can reach temperatures of up to 2,000,000°C (3,600,000°F).

Here’s the thing, though: They’re not actually spinning, which means they're not really tornadoes. This curious revelation comes courtesy of an international team of researchers, who presented the cumulative results of several of their studies at the European Week of Astronomy and Space Science (EWASS) in Liverpool this Friday.

Previous images, turned into small movies by the SDO, really do make them look like they’re spinning, but this simply isn’t the case; we’re just being tricked by what is essentially an optical illusion. We're certainly going to have to stop calling them "tornadoes".

“We have yet to come up with a more appropriate name, though one could call them 'oscillating pillars,'" the University of Glasgow's Dr Nicolas Labrosse, who presented the work, told IFLScience.

The problem with these furious fakers – thought to be rooted somewhere beneath the surficial solar corona, which prevents them from moving anywhere – is that they’d only really been seen in two dimensions in the past. Although they’ve been observed for around a century through various means, most of our best images have come courtesy of the aforementioned SDO.

These clearly show huge plumes, composed of magnetized superheated plasma, that resemble terrestrial tornadoes. Although it wasn’t thought that they behaved in a way that could be directly comparable to our tornadoes, they did appear to be spinning based on the imagery we had obtained.

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A video of a seemingly "spinning" tornado. SDO/NASA/Aberystwyth University

Being somewhat suspicious, and hoping to get a little more detail on these enigmatic twisters, astronomers from the Universities of Glasgow and Toulouse, the Paris Observatory, and the Czech Academy of Sciences decided to try something rather clever: apply the Doppler effect.

In astronomy, this most often comes up when you’re talking about redshift and blueshift. As waves of electromagnetic radiation, including visible light, are stretched or compressed, their waveforms also become spaced out or bunched up together, respectively. This also changes their frequency.

As objects in space move away from us, such as galaxies, their emitted light shifts to the lower frequency, longer wavelength end of the spectrum – and they’re “red-shifted”. The opposite leads to them becoming “blue-shifted”.

Astronomers can use very tiny variations in redshift and blueshift to work out the precise paths and velocities of objects in space. This includes those pesky solar tornadoes and their magnetic field lines, and when the team applied the Doppler effect calculations, they were perhaps surprised to find out that they weren’t actually spinning.

They do move, but horizontally, along magnetic field lines, for the most part. We’re only seeing tornado-like shapes and swirling patterns because of the line of sight we have – and, arguably, because we made a seemingly handy visual connection that stuck.

Although debate is expected, Labrosse added that they hope their results “provide strong arguments to favor the view that these giant tornadoes aren’t rotating.”

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