As a quasar, Ton 618 is believed to be the active galactic nucleus at the center of a galaxy, the engine of which is a supermassive black hole feeding on intensely hot gas and matter in an accretion disc. The light originating from the quasar is estimated to be 10.8 billion years old. With a mass of 66 billion M☉, TON 618 has a Schwarzschild radius (the radius of a black hole based on its mass) of 1,949 × 10¹⁴ meters. That's a black hole with a diameter of 389.8 billion kilometers, or 242.2 billion miles! Currently the largest known black hole is Ton 618. Some would say the largest object in the universe is UY Scuti, the largest known star. It's a red supergiant with a mass “only” 7–10 times the mass of the Sun, but with a radius up to 1,708 times the size! That's only 0.3% the size of TON 618, but obviously still stupendously large. TON 618 is as bright as 140 trillion suns and has a mass of about 66 billion suns. We know that many supermassive black holes formed early in the universe. For example, the quasar TON 618 is powered by a 66 billion solar mass black hole. Since its light travels nearly 11 billion years to reach us, TON 618 was already huge when the universe was just a few billion years old. We know that many supermassive black holes formed early in the universe. For example, the quasar TON 618 is powered by a 66 billion solar mass black hole. Since its light travels nearly 11 billion years to reach us, TON 618 was already huge when the universe was just a few billion years old. The mass of Ton 618 is estimated at around 66 billion solar masses, the mass of the Milky Way Galaxy is estimated at around 1.2 to 1.9 TRILLION solar masses. 60 billion out of 1.2 trillion is 60b/1200b, so 6/120 or 3/60 or 1/30. Ton 618 is around 1/30th of the mass of the Milky Way. Some would say the largest object in the universe is TON 618, a so-called quasar (a compact and extremely luminous active region at the center of a galaxy, which is presumed to be an active supermassive black hole). In the case of Ton 618, the enormous Lyman-alpha nebula surrounding it has the diameter of at least 100 kiloparsecs (320,000 light-years), twice the size of the Milky Way. TON 618 is as bright as 140 trillion suns and has a mass of about 66 billion suns. For comparison, all the stars in our galaxy combined share a mass of only 64 billion suns. That is, TON 618 is over 15,000 times more massive than Sagittarius A*. With the solar system being ~122 AU, TON 618 would swallow it 11 times over! Oh, and btw, this gargantuan supermassive black hole lies over 10 billion light-years away. If black holes evaporate via Hawking radiation, a supermassive black hole with a mass of 1011 (100 billion) M☉ will evaporate in around 2×10^100 years. TON 618 is now recognized as the 'accretion disc' of intensely hot gas swirling around a supermassive black hole in the centre of a galaxy in the Northern constellation of Canes Venatici.

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