This week on Radio Astronomy, hosts Brianna Smart and Zach Pace break down the discovery of the source of neutrinos. The source of these tiny, neutral, almost massless particles has been a mystery for over a hundred years. Known as ghost particles, billions of neutrinos pass through everyone each second. They cannot be directly detected, but can be caught interacting with matter due to the burst of light caused by the charged particles. The discovery was made at the IceCube Observatory at the South Pole, run by Wisconsin scientists. The observatory is made up of about 5000 light-detecting devices dropped deep within the ice, forming a cubic kilometer of monitored space. Using the observations, the source of some high-energy neutrinos has been discovered. The source turned out to be a blazar outside of our galaxy- a supermassive black hole in the center of a galaxy, shooting out energetic jets of material, emitting photons and neutrinos.