Swell

Swell fell for the red-giant phase because it taught them that endings can be spectacular.

"For a long time I thought getting old was sad," Swell admits. "Like a star just running down and going dim." They'd felt a little gloomy about it, honestly — all that steady burning, and then... what? A slow fade?

Then Swell watched a Sun-like star run out of hydrogen for the first time. "And it didn't just fade!" Swell says, cheeks already puffing at the memory. "Its core squeezed down tight and got hotter than ever — hot enough to start fusing a whole new fuel, helium! — and its outer shell ballooned out, huge and red and glorious, a hundred times bigger than before." Swell lets out a delighted breath. "It wasn't running down at all. It was transforming — growing into the biggest, boldest version of itself right at the end. That's when I understood: a star's old age isn't small and sad. It's the most enormous, dramatic thing it ever does."

Swell sat at a console in the Stellar Observation Room, eyes glued to the tracker, where a dot labeled Sun-like Star had started to flicker. "Oh, dear," Swell mumbled. "It's happening."

"What's happening?" asked Pip, who was untangling a knot in their space-boot laces nearby and not really paying attention.

Swell spun around, tunic rustling. "The star! It's running out!"

Swell held up a card of a bright yellow star. "This is a main-sequence star, like our Sun right now — happily burning hydrogen. But stars don't have endless fuel. Nothing does." Their voice dropped. "Hydrogen runs out." They picked up a card of a star with a tiny bright center. "When the core's hydrogen is gone, the core contracts—" Swell pulled their arms in tight, a little round ball — "and then—" they took a huge breath, cheeks bulging, tunic straining at the seams — "the outer shell expands!" Swell's whole body ballooned, slowly then faster, until they were nearly twice their size, red-orange stripes glowing. The tracker beeped; its dot swelled and turned fiery red. "Whoa!" Pip scrambled back. Swell pointed a chubby finger. "See? The star turns into a red giant — a hundred times bigger than before! The core gets hotter than ever—" puffing up more, face bright with effort — "hot enough to fuse helium!" "Helium? Like balloons?" Pip asked. "Exactly!" Swell wheezed, now nearly touching the ceiling. "A whole new way to make energy. This is the red-giant phase." Then, quieter: "Our own Sun will do this — in about five billion years. It'll swell so big it'll swallow Mercury, then Venus, then... Earth." Pip's jaw dropped. "Swallow Earth?" Swell nodded slowly and began to shrink, the air hissing gently out. "Yep. Stars get old. They change." Back to normal size, a bit tired but glowing with fascination, Swell murmured: "Hydrogen runs out. Core contracts. Shell expands. Helium fusion begins."