A MARTINEZ, HOST:
Good morning. I'm A Martinez. There's no sound in space, right?
(SOUNDBITE OF HUMMING)
MARTINEZ: That's sound released by NASA from the black hole at the center of the Perseus galaxy cluster. What you're hearing is pressure waves emitted from the black hole causing ripples in the cluster of stars' hot gas. But in my warped imagination, it sounds like an alien civilization screaming for their lives. I know; I'm a ghoul. It's MORNING EDITION. Transcript provided by NPR, Copyright NPR.