The Terrifying Scale of the Largest Black Hole We’ve Ever Found

The largest black hole ever found isn't just incomprehensibly massive, it's incomprehensibly uncertain. At the top of the scale, where black holes weigh tens of billions of suns and their event horizons swallow entire solar systems, the numbers that make headlines are not clean facts. They are estimates, wrapped in models, filtered through measurement techniques that were never designed for objects this extreme.

This video traces the full hierarchy of the most massive black holes known to science, from Sagittarius A*, the four-million-solar-mass anchor at the center of our Milky Way, to M87*, the six-and-a-half-billion-solar-mass giant whose shadow was photographed by the Event Horizon Telescope. From TON 618, the distant quasar whose sixty-six-billion-solar-mass estimate relies on the width of a single emission line, to Holm 15A*, the forty-billion-solar-mass monster measured through direct stellar dynamics. From the newly discovered Cosmic Horseshoe black hole at thirty-six billion solar masses, weighed using gravitational lensing for the first time, to Phoenix A, whose mass could be twenty billion or one hundred billion depending on which paper you read.

Sources:

Event Horizon Telescope Collaboration. (2019). "First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole." The Astrophysical Journal Letters, 875(1), L1. https://doi.org/10.3847/2041-8213/ab0ec7

Mehrgan, K., Thomas, J., Saglia, R., Mazzalay, X., Erwin, P., Bender, R., Kluge, M. & Fabricius, M. (2019). "A 40 Billion Solar-mass Black Hole in the Extreme Core of Holm 15A, the Central Galaxy of Abell 85." The Astrophysical Journal, 887(2), 195. https://doi.org/10.3847/1538-4357/ab5856

Melo-Carneiro, C.R., Collett, T.E., Oldham, L.J., Enzi, W., Furlanetto, C., Chies-Santos, A.L. & Li, T. (2025). "Unveiling a 36 billion solar mass black hole at the centre of the Cosmic Horseshoe gravitational lens." Monthly Notices of the Royal Astronomical Society, 541(4), 2853-2871. https://doi.org/10.1093/mnras/staf1036

van den Bosch, R.C.E. et al. (2012). "An over-massive black hole in the compact lenticular galaxy NGC 1277." Nature, 491, 729-731. https://www.nature.com/articles/nature11592

NASA Goddard. (2024). "NASA Animation Sizes Up the Universe's Biggest Black Holes." https://svs.gsfc.nasa.gov

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