 Gamma ray bursts are the most energetic and luminous electromagnetic events in the universe. They can release more energy in 10 seconds than our sun will emit in its entire 10 billion year expected lifetime. To understand these events, we need to take a closer look at gamma rays. Gamma rays are the highest energy form of light. The wavelengths are smaller than the diameter of a typical atomic nucleus. Here's an example of a gamma ray photon created when an excited cobalt atomic nucleus decays to a lower energy level. The gamma ray photon has 640,000 times more energy than the yellow light photon. And this is a relatively low energy gamma ray. Solar sources are extreme conditions in our Milky Way and other galaxies. Some are generated by transient events, such as solar flares and supernovas. Others are produced by steady sources like supermassive black holes that galaxy centers. Since June 2008, the Fermi Gamma Ray Space Telescope has been scanning the entire sky for gamma rays every three hours. Here's an all-sky map as seen by Fermi. The brighter gamma ray light is shown in yellow, and progressively dimmer gamma ray light is shown in red and blue. We see that the plane of the Milky Way is bright in gamma rays. Above and below the bright band, much of the gamma ray light is coming from outside of our galaxy. Here's a full spectrum composite image of the Cassiopeia A supernova remnant. Note the strong gamma ray emission area on the right. Gamma ray energies up to 7 trillion electron volts were measured here. But the energy from sources such as these spread out in all directions and weaken in intensity according to our familiar inverse square law. The gamma ray bursts, GRBs for short, first spotted in the 1960s, are focused and remain intense even as they move across the cosmos. Lasting anywhere from a few milliseconds to several minutes, they shine hundreds of times brighter than a typical supernova and about a million trillion times brighter than our sun. Here's the furthest and most powerful GRB ever detected. It occurred 12.2 billion light years away as determined by visible afterglow light seen by the European Southern Observatory in Chile. With a distance known, the strength of the blast can be calculated. This blast exceeded the power of approximately 5,900 Type 1A supernova. By the late 90s, 10 gamma ray bursts had been observed. This was enough to distinguish two distinct types. First, usually around a second or less, and long, usually around 30 seconds to a couple of minutes. It was thought that long duration bursts came from imploding stars collapsing into black holes. These are referred to as superluminous supernova, or hypernova, or collapsears. This theory was confirmed in 1998 when GRB 980425 was also found to be supernova 1998 BW in a spiral galaxy a hundred million light years away. But there has never been any confirmation that short bursts come from merging neutron stars. That is, until August 17, 2017.