Up to half of all the water in our Solar System predates the formation of the Sun.
Researchers at the University of Michigan wanted to know whether water formed along with the solar system or predates it. In a paper published in Science, they determined that between 30 and 50 percent of it - including water on Earth - did in fact exist about one million years before our Sun formed.
"Why this is important?" asked Carnegie Institution for Science's Conel Alexander, who contributed to the research. "If water in the early Solar System was primarily inherited as ice from interstellar space, then it is likely that similar ices, along with the prebiotic organic matter that they contain, are abundant in most or all protoplanetary disks around forming stars."
In other words, one of the fundamental requirements for life to exist can likely be abundantly found throughout the universe. "Our findings show that a significant fraction of our Solar System's water, the most-fundamental ingredient to fostering life, is older than the Sun, which indicates that abundant, organic-rich interstellar ices should probably be found in all young planetary systems," Alexander said.
How did the researchers come to this conclusion? It's all about deuterium, an isotope of hydrogen that has a neutron in its nucleus. Hydrogen normally doesn't have a neutron, but isotopes are variants of elements that have either more or fewer neutrons than usual. Water is composed of hydrogen and oxygen, and when the hydrogen is instead deuterium, we get something called "heavy water" - the extra neutron accounts for the added weight.
The researchers ran simulations to predict the ratio of water to heavy water that should be found in our solar system if all the water was created at the same time, but their results showed that the observed ratios are not compatible with this model - there is simply too much deuterium. Since all the deuterium we observe cannot have originated in our solar system, it must pre-date it and have been part of the dust cloud that ultimately formed the solar system.
"The implications of these findings are pretty exciting," said study co-author Ilse Cleeves. "If water formation had been a local process that occurs in individual stellar systems, the amount of water and other important chemical ingredients necessary for the formation of life might vary from system to system. But because some of the chemically rich ices from the molecular cloud are directly inherited, young planetary systems have access to these important ingredients."
The possibility of finding alien life somewhere out there just increased.