The Largest Known Black Hole Could Swallow Our Solar System Whole
Answers: “what is the biggest black hole?”
The black hole at the center of our galaxy, Sagittarius A*, weighs about 4 million Suns. It sounds enormous — until you meet the true giants.
TON 618 is an ultramassive black hole powering a distant quasar, and its measured mass is roughly 66 billion times that of the Sun.
Numbers that size stop meaning anything, so let’s translate:
- Its event horizon — the boundary of no return — is about 40 times the distance from the Sun to Neptune. Our entire solar system, every planet and orbit, would fit inside it thousands of times over.
- Light, the fastest thing in existence, would need around a week to cross its diameter.
- If you placed it where the Sun is, it would engulf not just the planets but a good chunk of the space between us and neighboring stars.
TON 618 announced itself the way all quasars do: by feeding. As matter spirals in, it heats to millions of degrees and blazes with the light of trillions of Suns — which is the only reason we can see it at all from over 10 billion light-years away.
And that distance carries a twist. Because its light took over 10 billion years to reach us, we’re seeing TON 618 as it was when the universe was young. Which means this monster grew to 66 billion solar masses fast — so fast that astrophysicists genuinely struggle to explain how. Black holes shouldn’t be able to eat that quickly. The universe’s biggest objects are also its biggest accounting errors.
Somewhere out there, TON 618 still exists, even larger now. What it has become in the 10 billion years since the light left — no one will ever know.