How many droplets did Trisolaris send to the Solar System?
Ten. On its way toward the Solar System, the Trisolaran fleet launched ten probes ahead of itself. Each was barely three meters long, shaped like a perfect teardrop, with a mirror-smooth shell made of strong-interaction material. The first one to arrive was nicknamed the "droplet" because of its shape, and that name ended up covering all ten.
The number ten is easy to miss, because the story keeps its camera fixed on the first arrival. That is the probe humanity's survey fleet sailed out to meet, and the one Ding Yi studied up close before realizing what its shell was made of. So the honest answer has two halves: ten were sent, but only one fought at the Doomsday Battle.
How many human ships did a single droplet destroy?
Roughly two thousand. After almost two centuries of technological buildup, humanity fielded a fleet of more than two thousand stellar-class warships and expected to win. One droplet erased the entire formation in under thirty minutes.
It moved at about 3,000 kilometers per second—around one percent of lightspeed—punching through each ship bow to stern like a bullet through paper, detonating the fusion fuel inside. Lasers reflected off its mirror surface, shells left no mark on the strong-interaction shell, and nuclear blasts couldn't catch it in vacuum. A full reconstruction lives in the Droplet Attack entry. The only survivors were the handful of ships whose captains fled the instant the shooting started—cowards in that moment, the only people who got it right in hindsight.
Why did just one droplet do all the killing?
Because in Trisolaran terms the droplet isn't a weapon at all—it's a low-end probe. Sending ten wasn't about needing ten to win. Wiping out two thousand warships is trivial for a single unit; the other nine had different jobs.
That "one is enough" design is the first concrete preview of the dimensional-strike logic that drives the back half of the trilogy. The point isn't that the enemy has bigger guns. It's that the gap between civilizations is so wide you don't even rate the use of a real weapon. The physics of why the shell is indestructible is unpacked in the droplet's material and terror.
What happened to the other nine droplets?
They blockaded the Sun. Humanity had discovered the Sun could act as a radio amplifier, capable of broadcasting a message to the whole galaxy. Trisolaris understood exactly what that meant: once humans grasped dark forest deterrence, they could use the Sun to broadcast Trisolaris's coordinates. So the remaining droplets took up positions around the Sun and physically cut that link.
The first droplet destroyed humanity's military; the rest cut off humanity's ability to retaliate. Ten probes were a single integrated blockade system, not ten redundant weapons. Seen that way, the choice to send "probes" rather than warships makes sense—Trisolaris was never afraid of the fleet. It was afraid of the one card humanity might flip to upend the table.
Was the droplet really just a probe, not a warship?
Yes, and that classification is the whole horror of it. Within Trisolaran technology the droplet ranks as reconnaissance hardware, yet it casually ended every spacecraft humanity had ever built. The beauty of the thing—the flawless curve, the perfect reflective skin—sitting against the slaughter it delivered is Liu Cixin's recurring theme: in this universe the most terrifying things tend to wear the most beautiful shapes. Ten were sent, one struck, and that distance between the numbers is the feeling the book wants you to keep.