The star that marks the heart of the scorpion is at death’s door. Sometime in the next million years or so, Antares is expected to explode as a supernova.

But astronomers don’t know exactly when that’ll happen. There’s no way to see into its core, which is where the fusion reactions that power the star take place. And with current technology, we can’t tell that the end is near by looking at the surface of Antares.

The star is many times the mass of the Sun, so when its nuclear engine shuts down, its core will collapse to form a neutron star or black hole. Its outer layers then will blast outward at a good fraction of the speed of light. But the star is so big that the shockwave won’t reach the surface for many hours, so it won’t begin to brighten for hours.

The shockwave is powered in part by neutrinos – particles created during the collapse. They almost never interact with other matter, so most of them will zip through the star at almost the speed of light. But there are so many of them that the rare times they do interact will help drive the blast.

As the neutrinos race through the galaxy, they’ll reach detectors on Earth hours before the surface of Antares begins to brighten – alerting us to the brilliant demise of a giant star.

Antares stands to the upper right of the Moon at nightfall, and leads the Moon down the southwestern sky later on.

We’ll have more about the scorpion tomorrow.

Script by Damond Benningfield