The Sun fired the biggest solar flare in six years at Earth yesterday, causing a radio blackout – and there could be another in hours.
Just after 5pm yesterday an X-class flare, the most powerful type, erupted from the Sun’s surface. A blast of electromagnetic radiation hit our atmosphere about eight minutes later, leading to communications blackouts over North and South America.
However, following in the flare’s footsteps is a second solar phenomenon known as a coronal mass ejection (CEM).
CEMs are huge clouds of solar plasma blasted out into space at millions of miles an hour. When directed towards Earth, they generally take two or three days to hit, but this one is expected any time now.
‘The US Air Force is reporting a Type II solar radio burst, which typically comes from the leading edge of a CME,’ reported the website SpaceWeather. ‘Based on the drift rate of the radio burst, the emerging CME’s velocity could exceed 4.7 million mph.’
The Earth is around 93 million miles from the Sun, meaning the CME will take around 20 hours to make the journey.
Like solar flares, CMEs can lead to communications blackouts as the charged plasma messes with the same level of the atmosphere used for bouncing signals off by communications systems.
But on the bright side, they can also give aurora a boost, meaning the Northern Lights could put on a particularly spectacular show tonight.
CEMs cause aurora by supercharging particles in the magnetosphere when they hit. This sends them rushing up and down the planet’s magnetic field lines between the poles.
Here they collide with oxygen and nitrogen in the upper atmosphere, exciting the atoms that then release visible light of different colours, including green, purple and pink – and recently, very rare orange aurora.
However, they could be less rare over the coming months as the Sun is particularly active right now. This is because it is reaching the most active part of its 11-year cycle, known as the solar maximum.
More sunspots – which often set off solar flares and CEMs – are visible on the surface, and more powerful eruptions have been spotted.
There have already been at least two major communications blackouts this year, and last month a huge ‘sunspot archipelago’ appeared on the Sun’s surface.
A number of ‘cannibal’ CMEs have also been spotted, where one CME is ‘eaten’ by a bigger, fast-moving CME.
But in a more surprising find, last week a ‘coronal hole’ appeared. Despite its name – and looks – it isn’t actually a hole in the Sun’s surface, but the magnetic field, and is more common during the solar minimum.
MORE : Earth hit by massive solar flare knocking out radio across US – and it won’t be the last
MORE : Triple whammy of solar storms heading for Earth could turn ‘cannibal’
MORE : No wonder the Sun is so angry right now – there’s a huge hole in it
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