New simulations suggest supernova explosions of the Universe’s first stars scattered the ingredients for rocky planets only 100 million years after the Big Bang, with water already present in some planet-forming disks.
This artist’s impression shows a field of Population III stars as they would have appeared a mere 100 million years after the Big Bang. Image credit: NOIRLab / NSF / AURA / J. da Silva / Spaceengine.
Some of the very first stars in the Universe were enormous and ended their lives in powerful explosions.
Known as Pop III supernovae, these catastrophic events scattered huge amounts of the chemical elements needed to build planets, such as carbon, oxygen and iron, into the surrounding gas.
“Our new paper shows that the precursors of terrestrial planets can form around low-mass, long-lived stars in the debris of the first cosmic explosions 100 million years after the Big Bang,” said University of Portsmouth astrophysicist Dr. Daniel Whalen.
“To put this into perspective, the Universe is about 13.8 billion years old, so this is remarkably early in cosmic history.”
A particular type of Pop III supernova, called a pair-instability supernova, is so powerful that it can blast out more than 100 times the mass of the Sun’s worth of heavy elements in a single explosion.
This material can enrich nearby clouds of gas to surprisingly high concentrations of heavy elements.
Those enriched clouds can then collapse under gravity and form a swirling disk of material around a young star, much like the disk from which our own Solar System formed.
“In our computer simulations of the early Universe, we found one such disk around a young star about 70% as massive as the Sun,” Dr. Whalen said.
“Within the disk, enough solid material accumulated to create several Earth-masses’ worth of planetary building blocks at roughly the same distance from the star as Earth is from the Sun.”
“Most surprisingly, the disk also contained substantial amounts of water, only a few times less than what was available when our own Solar System formed.”
“This means that any planets forming there could potentially have received water in a similar way to Earth, which is thought to have gained much of its water from material left over during the planet-building process.”
“Our findings suggest that the conditions for planet formation may have existed much earlier than previously thought.”
“If that’s the case, it raises an intriguing question: could potentially habitable worlds have appeared far earlier in the Universe’s history as well?”
The team’s paper will be published in the Astrophysical Letters Journal.
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Eduard I. Vorobyov et al. 2026. Planet Formation at Cosmic Dawn: Planetesimals in H2O-Rich Disks around Low-Mass Stars. ApJL, in press; arXiv: 2501.08375
