Large solar flare seen in extreme ultraviolet light, 1973.
© National Aeronautics & Space Administration / Science & Society
This picture taken from the Skylab space station on 19th December 1973, shows one of the most spectacular solar flares ever recorded. Solar flares are sudden outbursts of energy originating on the Sun's surface and projecting far into its atmosphere. They occur near sunspots on boundaries dividing areas with opposite magnetic fields. Temperatures inside flares can reach tens of millions of degrees Kelvin, and masive amounts of radiation are released acros the whole electromagnetic spectrum. The emisions from large flares can cause radio blackouts on Earth, and can be dangerous to astronauts beyond the protection of the Earth's atmosphere, which shields the planet from the most harmful radiation.