“Isn't what we call today really yesterday's tomorrow?” A profound thought from the heart of a cosmic Crab.

Shared in 2016 by NASA Hubble, this mesmerizing image of the Crab Nebula reveals one of the most thoroughly studied remnants left behind by a supernova explosion - in other words, a cosmic heart that continues to beat after the death of a star.

The neutron star at the center of the nebula (the rightmost of the two bright stars) spins 30 times per second, emitting pulses of radiation at regular intervals, like a clock. The Crab Nebula, which appeared in the sky about 1,000 years ago, is located about 6,500 light-years from Earth.

Image description:

Stars and gas swirl in a hazy image of the cosmos. Orange-red bands encircle the outside of the image and snake through the center; a handful of bright white stars are scattered, especially just right of center.

Credits: NASA and ESA