How many suns are there in the Three-Body Problem?
Three. The answer is baked into the title. "Three-body" comes from the three-body problem in celestial mechanics — the motion of three objects under their mutual gravity — and in the novel those three objects are the three suns of the Trisolaran system. Earth has one sun and a clockwork-stable orbit; Trisolaris orbits a system of three, and the gravity of three stars pulling on each other never settles into a predictable path. That single difference — one sun versus three — is the source of everything the Trisolarans suffer.
Why do three suns make the sky unpredictable?
With one sun, a planet traces a clean ellipse and you can calculate every sunrise millions of years ahead. Add a third star and the whole thing goes chaotic. Trisolaris is sometimes briefly captured by a single sun and enjoys a Stable Era of mild, orbit-regular weather — but that calm can shatter at any moment when the other two suns drift close and fling the planet into a Chaotic Era. In a Chaotic Era three suns can hang overhead at once and scorch the ground, or all three can recede and freeze the world solid.
Because no one can predict which era comes next, the Trisolarans evolved the ability to dehydrate their bodies into storable fiber and wait out the disasters. That biology is not an alien quirk — it is a survival strategy forced on them by having three suns instead of one.
How many planets did the three suns destroy?
Eleven. The Trisolaran system was born with twelve planets, and over the ages the three suns swallowed, burned, or ejected eleven of them, leaving only one — the Trisolaran homeworld. The planet the Trisolarans live on is the single survivor of twelve siblings, and it is alive only by luck. That "we could be next" dread is the psychological engine behind their desperate drive to colonize Earth. Under these three suns, Trisolaran civilization has been wiped out and rebuilt more than two hundred times, and almost every collapse traces back to the stars overhead.
Are the three suns based on a real star system?
Yes. The model is Alpha Centauri, the closest star system to our own and a genuine triple-star system: Alpha Centauri A, Alpha Centauri B, and the smaller, more distant Proxima Centauri. That is why the Trisolaran fleet has to cross roughly four light-years to reach Earth — Proxima sits about 4.2 light-years away. Liu Cixin took the real three-sun neighbor in our night sky and dropped in the famous physics problem that has no general analytical solution, so the science and the cruelty of the story lock together exactly.
How does the Three-Body story finally end for the suns?
One of the three suns destroys everything. In Death's End, a higher civilization launches a dark forest strike at the Trisolaran system, and the photoid it fires slams into one of the three stars. The struck sun erupts, and the Trisolaran homeworld — along with everything it clawed out of millions of years of chaos — is annihilated in the blast of its own star. It is the coldest irony in the whole setup: the Trisolarans spend their entire history fleeing the tyranny of three suns and crossing four light-years to seize Earth, only to be killed by one of those same three suns in the end. The number never changes — three — only the way they kill.