Water is a key element in the formation of stars and planets. A new study reveals that the water on Earth is much older than the Sun itself, potentially billions of years older, and originates from the interstellar medium, the space between stars. By examining the water on the protostar V883 Orion, located 1,305 light-years from Earth, scientists have uncovered a probable link between the water in the interstellar medium and the water in our solar system.

The research team, led by John Tobin of the National Science Foundation’s National Radio Astronomy Observatory, published their findings in Nature. They describe a clear path that water follows through the universe, from its creation in interstellar clouds to its presence on planets and in comets. The discovery of water on V883 Orion is a breakthrough, as it helps trace this path of water from the early stages of star formation to the formation of planetary systems.

Before this study, scientists could link the water on Earth to comets and protostars to the interstellar medium, but the connection between protostars and comets remained unclear. The water detected on V883 Orion changes that. It proves that water molecules in that system have a similar ratio of deuterium and hydrogen as those found in our solar system, establishing a direct link between the two. This suggests that water molecules in our solar system are far older than previously thought, predating the formation of the Sun and planets.

Margot Leemker, an astronomer at Leiden University and coauthor of the study, explained that the bulk of water in the interstellar medium forms as ice on tiny dust grains in space clouds. These clouds eventually collapse under their own gravity, forming young stars and protoplanetary disks. The water from these clouds remains unchanged throughout these stages, becoming part of new solar systems, planets, and comets.

By studying the water on V883 Orion using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers were able to observe this ancient water because the protostar was hot enough to turn the ice into gas. This allowed them to measure the composition of water and confirm that it had remained consistent across various stages of solar system formation.

This new finding fills a critical gap in understanding the origins of water in our solar system. “Until now, the chain of water in the development of our solar system was broken,” Tobin said. “V883 Orion is the missing link in this case, and we now have an unbroken chain in the lineage of water from comets and protostars to the interstellar medium.”

Merel van ‘t Hoff, an astronomer from the University of Michigan and coauthor of the study, added that this discovery suggests planetary systems, including ours, have received vast amounts of water during their formation. The study also offers a glimpse into the early history of our solar system, suggesting that the water we see on Earth today has traveled through the universe for billions of years, unchanged since the time it formed in interstellar clouds. This revelation not only reshapes our understanding of Earth’s water but also provides insights into the water present in other planetary systems.