20 looks in 20 yrs: Space photo collection shows sun’s dynamic makeovers
SOHO is a European Space Agency spacecraft floating between the earth and the sun. Its extreme ultraviolet Imaging Telescope produces high resolution images of the sun’s atmosphere – or the corona – allowing observers to see when it’s bustling with activity and when it’s calm.
Taking such images from earth would be impossible, because the planet’s atmosphere blocks 75 percent of ultraviolet radiation.
The 20 images of the sun were taken over the 20 years of SOHO’s
scientific exploration, all of them in springtime.
When put together they create a clear picture of the 11-year solar activity cycle, with the brightest images occurring around the time of maximum solar activity.
“At these times, the magnetic field of the Sun is highly
dynamic, changing its configuration and releasing energy, partly
in the form of ultraviolet radiation into space,” ESA
explains in a press release.
One of the greatest puzzles about the sun is the extremely high temperature of its corona, the plasma aura stretching millions of kilometers from the Sun. Measuring some 2 million degrees Celsius, its temperature far surpasses that of the star’s surface, which is only about 5,700°C. The sun’s magnetic activity is suspected to be the cause of the disparity, but the exact mechanism remains unknown.