Some quick work by astronomers nabbed the optical flash from a huge explosion caused by two neutron stars colliding nearly three-quarters of the way across the observable Universe. This is the second farthest short gamma-ray burst ever seen, the very farthest visible flash of light from one ever seen, and a rare beast indeed.
Gamma-ray bursts (or GRBs) are some of the most powerful and violent explosions in the cosmos. They were first detected in the 1960s, but their true nature didn't start unfolding until the 1990s, when we learned they were extremely far away and therefore ridiculously powerful. Like, emitting in a few seconds the same energy the Sun will over its entire 12 billion year lifetime powerful.
They come in two flavors: Long (longer than 2 seconds on average) and short (you guessed it: shorter than 2 seconds). Long ones have a number of different sources, but in general come from massive stars exploding as supernovae, and their cores collapse to form black holes. Not every supernova generates a GRB, but when they do the explosion is incredibly energetic, allowing us to see them at vast distances.
Artwork depicting the moment of collision between two neutron stars. The ...