Interactive · Black holes
How big is a black hole?
Drag the mass slider — from a collapsed star to a cosmic monster — and watch the event horizon grow against Earth, the Sun, and the entire solar system.
The honest questions
How is a black hole's size measured?
By its event horizon — the boundary past which nothing escapes. For a non-rotating black hole this is the Schwarzschild radius: about 2.95 km per solar mass of the hole. Double the mass, double the radius — but eight times the volume.
How many Earths fit inside TON 618?
Roughly 28.7 sextillion (2.87 × 10²²). Its event horizon is about 1,300 AU across — it would swallow our entire solar system thousands of times over.
Could a black hole swallow the solar system?
Only a supermassive one. Sagittarius A*, our galaxy's central black hole, wouldn't even reach Mercury if placed at the Sun's position. But M87* would swallow everything out past Neptune, and TON 618 would keep going more than a thousand AU further.
Are these sizes exact?
They use the Schwarzschild radius for a non-rotating black hole. Real black holes spin, and spin shrinks the event horizon somewhat — so treat these as honest, slightly generous estimates.