Witnessing a neutron star violently crash into another has helped astronomers uncover secrets of the universe including how gold was created. Neutron stars are the collapsed centers of stars. These two neutron stars circled each other at a very fast rate, getting closer and closer. Then they crashed into each other in an event called a kilonova. This collision created a burst of gamma rays, or electromagnetic energy, and gravitational waves, which make a weak signal when they reach Earth. Vicky Kalogera is an astrophysicist with Northwestern University near Chicago. She explains what the astronomers heard and saw two months ago. So this is the first time that we hear the death spiral of two neutron stars. And we also see the fireworks that came from the final merger. What they saw was a bright, blue light.