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X2 Solar Flare heading our way - Aurora Alert!

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Helen Czerski Helen Czerski | 18:00 UK time, Wednesday, 16 February 2011

d ~ 120'921'600 km: day 47

The impact of the Earth's orbit around the Sun can be seen on Earth in the form of weather phenomena amongst many other things but weather isn't just something that happens on Earth. Our Sun has its own weather, but you don't have to be on the Sun's surface to know about it. Yesterday at 2am GMT, a particularly violent bit of solar weather twisted itself free and was launched towards us here on Earth.

Before you run to fetch your tinfoil hat and hide in the basement, let me just say that this isn't that unusual. Last time it happened you probably didn't notice it at all. Still, this event (classed as an X2 solar flare) is the strongest solar flare in the past four years that has been directed towards Earth.

The Sun and the Earth both have magnetic fields, but the Sun's is far more complex. In an active region of the Sun, the sort of place where a sunspot might form, the magnetic field can be 4000 times larger than normal. These complicated twisted magnetic fields store huge amounts of energy, and when they suddenly readjust and untwist, all that energy has to go somewhere. A lot of it is converted to light of all wavelengths, from radio waves to x-­‐rays. This massive outburst of light is a solar flare.

Intense flash of extreme ultraviolet radiation from the Sun 15.02.2011

Courtesy of NASA

Yesterday's X2 event was so powerful that it also caused a coronal mass ejection, which means that a giant plume of energetic electrons and protons was thrown off the sun's surface. These ones happened to be accelerated more or less right towards us.

The light from the solar flare travels at the speed of light, and it took about eight minutes to reach us after the X2 event. That's how we know that it happened. But all those energetic particles are travelling much more slowly (around 710km per second), and so they'll take 24-­‐48 hours to reach us. Right now, we're in the gap between the two arrivals. When those particles do arrive, they'll disrupt the Earth's magnetic field and may cause a geomagnetic storm. There's a chance that this will disrupt some long-­‐range radio communications and power networks. But the good news for me in the UK is that there's a chance of seeing aurora around our latitude.

View from space of northern lights

Courtesy of NASA

Keep an eye on the sky if it's clear tonight, and if you see any coloured light, you may be seeing the direct effect of some of the Sun's weather visiting us here on Earth. I've never seen the aurora - I'll definitely be watching with excitement. If you do see anything that might be an aurora, email us with your photos!


  • Comment number 1.

    Thanks Helen Czerski for such a interesting article.

    I interested to know about sun,galaxies and Earth.

  • Comment number 2.

    Sorry to disappoint Helen, but the weather will get in the way of the northern lights tonight. Cloudy skies are expected across pretty much the whole of the UK. There's a reminder that we're still not out of winter too, with heavy snow forecast for the Pennines and Scottish hills.
    I was lucky enough to see the Aurora Australis or southern lights on several occasions when working in the Antarctic back in the early 1980s. It is the most impressive natural phenomenon that I've ever seen. The sheer scale and speed of movement of the waving curtains of light is staggering.
    Good news is that the sun is moving back into a more active phase of it's cycle, so the chance of seeing aurora will increase over the next couple of years.

  • Comment number 3.

    Thanks for your comment, Peter. I'm sorry to hear that cloud will probably block the view for everyone - I'd hoped that at least someone would get a peek! I've got my fingers crossed that it won't be too long until the next opportunity. It does sound like an amazing thing to see, and I love the images of the aurora from space. I wonder whether they'll be able to see them from the International Space Station.


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