Aldebaran, the bull’s bright eye, puts in one final good evening showing tonight. It’s close below the Moon after sunset. It’s so low in the sky that it would be hard to spot on its own. But its proximity to the Moon will help it stand out.

Aldebaran is at the end of its “normal” lifetime, so it’s undergoing a series of changes. Those changes cause its outer layers to puff up, making Aldebaran much brighter.

It’s all building up to the star’s final stage of life: a white dwarf — a stellar corpse more than half as massive as the Sun but no bigger than Earth.

The star will reach that point when its core can no longer produce nuclear reactions. The core will be a ball of carbon and oxygen. It’ll be squeezed so tightly that a teaspoon of its matter would weigh tons.

As it reaches that point, Aldebaran’s outer layers will puff away into space, exposing the dying core. Thanks to the final smattering of nuclear reactions around the core, it’ll be extremely hot.

As the reactions die out, the star will lose most of that heat and quickly start to fade away. The dead core will still be quite hot, but faint. It’ll then slowly radiate the rest of its heat into space — eventually leaving a black dwarf. That’ll take some time, though. In fact, the universe hasn’t been around long enough for even a single white dwarf to completely cool off. So the eye of the bull will shine — albeit faintly — for a long time to come.

Script by Damond Benningfield