(Image: NASA/GSFC/SDO)
A massive solar eruption on 26Â October was the sixth large flare since 19Â October, all emanating from one gigantic sunspot called ARÂ 12192. Measuring 129,000 kilometres across, it’s the largest sunspot since 1990. For comparison, that’s a spot 10 times the diameter of Earth. Does it pose dangers to us?
Earth’s atmosphere protects life on the surface from space weather, but the radiation from powerful flares can disrupt GPS and radio communications.
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The US National Oceanic and Atmospheric Administration’s Space Weather Prediction Centre said that radio communications issues could be expected throughout the Atlantic Ocean, in South America and western Africa. .
, an astrophysicist at NASA, says the timing of the outburst is not surprising. “We’re just past the peak of the 11Â year cycle,” she says, referring to the cycle of activity the sun tends to follow. “Just when we begin this drop, that’s when the biggest sunspots and strongest flares tend to happen.”
Space spitting
The sunspot is also unusual in that it hasn’t produced any coronal mass ejections, which spit billions of tonnes of solar material into space. Fast moving particles from these events interacting with Earth’s atmosphere cause the auroras seen in northern and southern latitudes.
“Generally speaking, 90Â per cent of sunspots produce coronal mass ejections,” says Guhathakurta. “This sunspot has not produced any. That’s why you’re not seeing auroras or the big magnetic storms.”
So why are we seeing prolific solar activity without the coronal mass ejections? There’s not a neat answer, says meteorologist at the University of Reading, UK. “We can get big flares without coronal mass ejections, but we can’t get coronal mass ejections without flares.”
It could well be that there will be some coronal mass ejections, but they will happen once AR 12192 has rotated to the other side of the sun – in which case we will have got off lightly, Owens says.
NASA has new spacecraft trained on the sun for AR 12192. The – known as STEREO and operated from the Goddard Space Flight Center in Greenbelt, Maryland – will let solar physicists track the massive sunspot as it moves around the sun and out of Earth’s line of sight.
“We are all watching [the sunspot] with gaping jaws,” says Guhathakurta.
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