When the Nobel Foundation awarded Ray Davis and Masatoshi Koshiba the 2002 Nobel Prize in Physics, it could have chosen to emphasize any of their many accomplishments. Davis made his name detecting neutrinos from the sun—the first of these notoriously elusive particles ever seen from beyond our planet—and Koshiba discovered them coming from the great supernova explosion of 1987. Their work was an experimental tour de force and helped to establish that neutrinos, which theorists had assumed were massless, in fact have a small mass. Yet the Nobel Foundation recognized Davis and Koshiba, above all, for establishing a new branch of science: neutrino astronomy.
With their work, neutrinos graduated from a theoretical novelty to a practical way to probe the universe. In addition to studying neutrinos to glean the particles’ properties, scientists can now use them to lift the veil on some of the hidden mysteries of the universe. In an undertaking akin to the construction of giant optical telescopes a century ago, astronomers have been designing and building vast neutrino telescopes in anticipation of seeing new wonders. These observatories have already caught tens of thousands of neutrinos and made pictures of the sun in neutrinos. Neutrinos from other cosmic sources are hard to tell apart from those produced in Earth’s upper atmosphere, but instruments should be able to do so by this time next year.