A neutron star collision detected by gravitational waves is Science's 2017 Breakthrough of the Year.

Gravitational waves are ripples in time-space that only occur under a handful of extreme cosmic conditions.

Data collected by the Fermi Space Telescope provide conclusive evidence that supernovae are the source of the speedy, energetic particles called cosmic rays, an international research team reports.

These charged particles, which are mostly protons, continuously assail the planet from outer space. There is general consensus among scientists that supernova remnants (the leftovers of a supernova explosion) are the sources of cosmic rays, but the final proof has been elusive because cosmic rays are deflected on their way to Earth.

NASA’s Swift satellite has captured an event in the cosmos like nothing ever seen before, researchers say in the 17 June issue of Science. A high-energy gamma-ray burst known as Sw1644+57, located at the center of a small, star-forming galaxy, is burning much longer and much brighter than astronomers had expected it to—and two separate teams of researchers are trying to figure out why.