"The most revolutionary picture of the 20th century"
It's not a shot of a group of soldiers raising a flag on Iwo Jima, not even Marilyn Monroe standing over an air vent in a white dress. CERN theoretical physicist Alvaro De Rujula thinks the title should go to this blurry picture of the Sun. Why? Because it shows the Sun´s core, which is usually invisible to us, and because it was taken not with light but with neutrinos, ghostly particles that rarely interact with matter.
Light usually takes thousands of years to work its way from the core to the Sun´s surface before making the 8 minute journey to Earth. Neutrinos, on the other hand, zip straight out from the Sun´s heart but their disinclination to interact with matter also makes them extremely hard to detect. The camera used for this picture was a vast tank containing 50,000 tons of water 1 kilometer underground in a mine in Japan. The Super-Kamiokande detector took the picture in the mid 1990s with an exposure lasting 500 days. So, as well as being the last century's most remarkable picture, it may also have been among the most expensive to produce.