Supermassive black holes thought to be the heavyweights of the early universe are far smaller than imagined, say astronomers.
Scientists have peered into the centre of an infant galaxy - located 12 billion lightyears from earth - for the first time using a powerful new instrument.
They found that the supermassive black hole at its heart was ten times smaller than expected.
Experts say the finding suggests we have been overestimating the size of the biggest black holes in the early universe for years.
If confirmed in other galaxies, it solves a puzzle of how these early supermassive black holes can grow very big very fast - they are simply not that big.
The study, to be published in the journal Astronomy and Astrophysics, was carried out by the GRAVITY+ collaboration which includes University of Southampton scientists.
Professor Seb Hoenig of the University of Southampton, GRAVITY+ co-investigator and co-lead of its Extragalactic Science Working Group, said the findings are a revelation of cosmic proportions.
He added: "We have been wondering for years how it's possible we discovered all these fully grown supermassive black holes in very young galaxies shortly after the Big Bang. They shouldn't have had the time to grow that massive.
"Our results suggest the methods to weigh these black holes used previously are just not working reliably in the early universe.
"It could lead to a re-evaluation of our models of cosmic evolution."
Experts made the intergalactic discovery using an advanced astronomical instrument, called GRAVITY+, which combines the light of four of the world's largest optical telescopes at the European Southern Observatory's Very Large Telescope in Chile.
They looked at an ancient quasar - a galaxy with a black hole so old and bright it looks like a cosmic beacon from the dawn of time.
The instrument gazed into the heart of the quasar, revealing the spiralling motion of hot gas about to be swallowed by the supermassive black hole, which is about 800million times the mass of our own Sun.
This motion was key to making this precise measurement of the black hole mass.
Lead author Dr Ric Davies from the Max Planck Institute for Extragalactic Physics in Germany said: "Our result is reliable because it's based on the actual motion of the gas.
"Many studies using the new James Webb Space telescope make use of scaling laws that might not hold at these early times.
"If our findings are typical, it means black hole masses in the early Universe may have been systematically overestimated."
The study also revealed that the supermassive black hole is consuming gas at an unbelievable rate, much faster than commonly thought possible.
This feeding frenzy is sending out a powerful outflow of gas which may have tricked telescopes into thinking the giant was much bigger.
Prof Hoenig added: "Most of the gas falling towards the supermassive black hole is being violently blasted away rather than feeding it.
"Think of it like a cosmic hairdryer set to maximum power: the intense radiation around it is blowing everything away that approaches it."
The GRAVITY+ collaboration is led by the Max Planck Institute for Extraterrestrial Physics and includes the University of Southampton as well as institutions in France, Germany, Portugal and Belgium.
The work was carried out in partnership with a Max Planck Partner Group in Beijing and colleagues at the Australian National University.
Read the study at https://arxiv.org/abs/2509.13911 .
