The sun is seething with tornadoes tens of thousands of kilometres tall that could wreak havoc on Earth. The tornadoes may cause dangerous solar eruptions that interfere with radio and GPS signals and could even damage electrical grids.
These stellar whirlwinds are found at the bases of enormous loops of plasma that shoot from the sun鈥檚 surface, called prominences. When a prominence becomes unstable, it can blast some of that plasma out into space in what鈥檚 called a coronal mass ejection (CME).
The prominence tornadoes appear similar to tornadoes on Earth and are probably caused by twisting magnetic fields, but recent measurements have shown that may not actually be spinning.
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Teimuraz Zaqarashvili at the Space Research Institute of the Austrian Academy of Sciences and his colleagues examined data from a NASA spacecraft called the Solar Dynamics Observatory to see how prominence tornadoes affect the stability of the plasma loops where they reside.
Tornado watch
Looking at data from 2011, they identified 361 tornadoes, 166 of which they were able to follow until the tornadoes dissipated. When the tornadoes violently collapse they unbalance the prominences above them, which then flings plasma into space.
The researchers found that 48 per cent of the tornadoes they watched underwent this process, 50 per cent triggered some sort of internal motion or instability in the prominence but no CME, and only 2 per cent caused no activity.
Zaqarashvili says that the tornadoes may cause CMEs by storing and then releasing magnetic energy. Their whirlwind form is a result their curled and twisted magnetic fields, and when the twist becomes too large, instabilities make the tornado collapse and release its stored energy into its host prominence, causing it to erupt. 鈥淭he instability in the tornadoes really destabilises the entire prominence,鈥� says Zaqarashvili.
The tornadoes had lifetimes ranging from 7 to 398 hours, and the mean lifetime of tornadoes that led to CMEs was between 25 and 75 hours. So, when we spot a tornado forming on the sun, we can expect a CME to occur one to three days later.
鈥淲hen a CME hits the Earth鈥檚 magnetosphere, it generates magnetic storms, and this may affect satellites, telecommunication systems, and even human health,鈥� says Zaqarashvili. 鈥淪o it is very important to predict CMEs, and that can be done by looking to the tornadoes.鈥�
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