Evidence for Supernovas Near Earth

NASA says there is Evidence for Supernovas Near Earth.

Once every 50 years, more or less, a massive star explodes somewhere in the Milky Way.  The resulting blast is terrifyingly powerful, pumping out more energy in a split second than the sun emits in a million years.  At its peak, a supernova can outshine the entire Milky Way.

It seems obvious that you wouldn't want a supernova exploding near Earth.  Yet there is growing evidence that one did—actually, more than one. About 10 million years ago, a nearby cluster of supernovas went off like popcorn.  We know because the explosions blew an enormous bubble in the interstellar medium, and we're inside it."

Astronomers call it "the Local Bubble." It is peanut-shaped, about 300 light years long, and filled with almost nothing. Gas inside the bubble is very thin (0.001 atoms per cubic centimeter) and very hot (roughly a million degrees)—a sharp departure from ordinary interstellar material.