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With Soho, the researchers were only able to take images in the upper section of the corona - the outer part of the Sun’s atmosphere. Stereo's Extreme Ultraviolet Imager (EUVI) instruments monitor the Sun at four wavelengths, which allowed astronomers to see how the wave moved through the different layers of the solar atmosphere. "We were able to show for the first time that this wave actually propagates almost all the way from the surface of the Sun to high up in the Sun's atmosphere," said Dr Gallagher.