There goes the neighborhood. This artist's conception represents a recently discovered and unimaginably huge explosion that occurred 10 billion years ago in the galaxy SMM J1237+6203. In the current Monthly Notices of the Royal Astronomical Society, astronomers report that the blast released energy equivalent to the detonation of trillions of nuclear bombs each second for millions of years. Whether caused by matter ejected from a supermassive black hole or by simultaneous supernova explosions of giant stars, the event removed so much material from the galaxy that star formation there stopped. The team will now search for similar blasts in other ancient galaxies to determine if they could have put the brakes on star birth across the early cosmos.