A subatomic particle with very small mass and zero charge, that rarely interacts with matter. Many quadrillions of neutrinos emanating from the core of the Sun pass through your body every second, but you'd never know it. Because of their ghostly properties, neutrinos are extremely difficult to capture and measure, but several super-sensitive neutrino detector arrays are now in operation around the world. Unlike optical telescopes, which can only see the surface of the Sun, neutrino telescopes might soon let us directly observe the solar core, so we can test our theories of thermonuclear fusion reactions.
A particle with no charge and little or no mass that is ejected from the nucleus at the same time as an electron or positron.
A group of leptons that have little, if any, mass. Since they are also electrically neutral, their most important interaction with other particles is the weak force. There is one neutrino for each of the charged leptons. See also: lepton, weak force, Debriefing, Journey - Neutrino