Neutrinos are strange subatomic particles that travel through the galaxy in straight lines, harmlessly passing through regular matter, and with their neutral charge they are free of the influence of magnetic fields. As such, neutrinos convey a lot more information than their diminutive stature suggests, leading astronomers back to their origins in high-energy cosmic events, like gamma-ray bursts, supernovas, black holes, or star formation. (There are other, less-interesting neutrinos produced by nuclear reactions, within the sun, or sometimes in manmade accelerators, but those carry less energy and are easy to distinguish from the high-energy, deep-space neutrinos.)