Laura Chomiuk

Terzan 5 is a globular star cluster, a tight swarm of hundreds of thousands of stars squeezed into a sphere a few dozen light-years across. In such a crowd, stars exchange matter and spin each other up, and some turn into pulsars — rapidly rotating neutron stars that emit radio pulses like lighthouses. New images taken with the Karl G.

Radio telescopes listen to the sky like sensitive ears: they catch the whispers of distant explosions, the hum of galaxies, the crackle of pulsars. But sometimes they pick up a sound that isn't in the catalogs. In 2003, such a sound emerged in the constellation Aquila — a spot in the sky that had been quiet until it suddenly began to speak.