What if Earth-like planets existed before the first galaxies? Scientists have an answer

Earth-like rocky planets may have formed much closer to the birth of the universe than previously thought.

For a long time, the understanding was that the universe didn’t have its first rocky planets until billions of years after the Big Bang. But a study, published last month in The Astrophysical Journal Letters, suggests that favorable conditions might have developed just about 100 million years into the universe’s lifetime. 

For perspective, the earliest known galaxy, designated MoM z14, existed just 280 million years after the Big Bang.

For the study, the researchers tracked the evolution of what are referred to as ‘Pop III supernovae’ using simulations. They found that these supernovae, which release more than 100 solar masses of material during a single explosion, seeded nearby gas clouds in the early universe with heavy elements. As these gas clouds came together, drawn by gravity, they formed rotating discs around young stars.

These discs were not too different from the one that resulted in the birth of our own solar system.

"In our computer simulations of the early Universe, we found one such disc around a young star about 70 percent as massive as the Sun,” said co-author Dr. Daniel Whalen from the University of Portsmouth’s Institute of Cosmology and Gravitation, in a statement published on Science Daily. This disc contained several Earth-mass worth of planetesimals—building blocks of planets—some of which were at around the same distance from the star as Earth is from the Sun.

What is even more interesting is that the researchers found water in the disc. Moreover, the quantity was just a few times less than what our solar system had access to during its formative days.

This indicates that water might have reached those planets in the same way it reached Earth—from what was left after the planet formation process.

As spectacular as the findings are in themselves, they also hint at an even more fascinating possibility of habitable worlds existing near the dawn of the universe.

“Just because there are planets forming doesn’t mean there’s life, of course, but the ingredients are being put in place pretty much as early as they possibly could be,” said astrophysicist Jarret Johnson of the Los Alamos National Laboratory in New Mexico, who wasn't part of the study, according to ScienceNews.