A star that’s about to undergo some big changes highlights the head of Cetus, the whale or sea monster. It probably will become unstable, then blow its outer layers into space to form a colorful bubble.

Menkar — from an Arabic name that means “the nostril” — is low in the east at nightfall and high in the south around midnight. It’s the second-brightest star in the constellation, and the brightest in the character’s head.

Menkar is classified as a red giant. It’s far beyond the prime of life. It’s converted the original material in its core to carbon and oxygen, which are basically just sitting there. All the action is taking place in a couple of shells of material around the core. In the inner shell, helium atoms are fusing together to make more carbon and oxygen. And in the outer layer, hydrogen is fusing to make more helium.

Before long, the star is likely to start puffing in and out like a beating heart. That phase won’t last long. And at its end, the star’s outer layers of gas will slough off into space. They’ll form an expanding shell of gas and dust. It might form a simple bubble, or it might be sculpted into something else — an hourglass, a butterfly, or some other beautiful shape.

The nebula could remain visible for tens of thousands of years. After that, only the star’s dead core will remain: a white dwarf — a dense ball as massive as the Sun but not much bigger than Earth.

Tomorrow: a violent merger.

Script by Damond Benningfield

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