The neutrino is a very difficult particle to deal with experimentally, predominately because it has no electric charge and is believed to contain a very tiny mass. The neutrino was first hypothesized to explain the conservation of energy and momentum in the beta decay reaction and was believed to be massless. In 1956, the neutrino was actually detected experimentally and its existence was confirmed. In 1962, it was discovered that neutrinos come in three types (or flavors): the electron neutrino, the muon neutrino and the tau neutrino. The major source of neutrinos found on Earth is the Sun; the Sun is a thermonuclear fusion reactor that produces tons of electron neutrino and these then travel to the Earth. When scientists set out to determine the quantity that arrives on Earth, they found that their experimental value did not match the theoretical quantity and this problem became known as the solar neutrino problem. Eventually it was believed to be resolved by theorizing that neutrinos, under the proper conditions, are actually able to transform between the three different flavors and this became known as the neutrino flavor oscillation. However, two questions that have still not been resolved in regards to the neutrino is the mass of the neutrino and whether or not the neutrino is a Majorana particle (that is, is it its own antiparticle, like the photon or Z boson).