Evidence of Water on Young Planet System Suggests Earth May Have Always Been Wet

Astronomers have discovered water vapour in a young planetary system using the James Webb Space Telescope (JWST). This finding suggests that Earth may have formed with water already present, rather than having it delivered later.

The system, known as PDS 70, is located about 400 light years away and consists of a star encircled by two massive gas discs with a gap between them. The outer disc is where two large exoplanets, each several times bigger than Jupiter, are believed to exist. The inner disc contains the necessary rocky materials for planet formation.

The team, led by Giulia Perotti from the Max Planck Institute for Astronomy in Germany, observed the PDS 70 system using the JWST and were surprised to find signs of water in the inner disc. This is unexpected because previous observations of similar discs had found no water. Moreover, water was not expected to survive the intense radiation near a star. However, the researchers believe that the water managed to survive for millions of years near PDS 70, likely due to shielding from other particles in the area, despite temperatures reaching upwards of 300°C.

This discovery suggests that if Earth-like planets were to form in the inner disc, they would contain water from the start. This finding contributes to the ongoing debate regarding whether rocky planets form with water or acquire it later through asteroid impacts. It provides strong evidence in support of the theory that rocky planets form with water already present.

“PDS 70 is a star similar to our sun, just younger and cooler,” explains Perotti. “By observing it, we can understand how the planets in our solar system formed and what their chemical composition was before they fully developed.”

Perotti and her team are continuing to observe the PDS 70 disc to further study its contents and gain insights into the formation of rocky worlds like Earth.