A future super-giant “onion” perches close to the Moon at dawn tomorrow. It’s the star Antares, the bright heart of the scorpion – one of the most impressive stars in the galaxy.

Antares is a supergiant. It’s roughly a dozen times as massive as the Sun, and hundreds of times wider. Because it’s so heavy, gravity squeezes its core tightly. That revs up the nuclear fusion in the core.

Like all stars, those reactions initially fused hydrogen to make helium. In the Sun, hydrogen fusion will last about 10 billion years. In Antares, though, it lasted a little more than 10 million years.

When the hydrogen in the core was gone, the core shrank, making it hotter – hot enough for the helium to fuse to make carbon and oxygen. That process will last about one million years. Then the carbon will fuse to make heavier elements, and so on. Each step takes less time than the one before. In the final step, silicon will fuse to make iron – a step that takes just a few days.

The lighter elements won’t all go away, though. Instead, the “ash” from each step will form layers around the core – like an onion. But that structure won’t last. The core can’t get hot enough to fuse the iron. Gravity will win out, and the core will collapse – forming an ultra-dense neutron star.

Everything outside the core will blast outward at a few percent of the speed of light. Supergiant Antares will explode as a supernova – an impressive end for an impressive star.

Script by Damond Benningfield