Neutrinos are sub-atomic particles that carry no charge and are so tiny that, when traveling through space, can pass right through the Earth undetected and not interact at all with the atoms that make up the Earth! Neutrinos are so hard to detect at all that scientists have had to build elaborate devices to try and find direct evidence of them at all.
The Super-Kamiokande neutrino detector in Japan shown here was designed to detect these miniscule particles and is filled with 50,000 tones of water when in operation. A neutrino passing through the detector can sometimes produce a very faint flash of light, which is detected by the 13,000 photomultiplier tubes lining the inside the detector, one that gave scientists the first clear evidence that neutrinos have mass...
