Earth’s Water Older Than The Sun — And Possibility For Extra-Terrestrial Life
Up to about half of the water in the solar system — including the Earth’s oceans — is older than the formation of the sun, according to a paper published on Thursday in the journal Science.
A team of scientists, led by L. Ilsedore Cleeves from the University of Michigan, revealed in the report that almost 30 to 50 percent of the water in the space was around even before the birth of the Sun — that’s more than 4.5 billion years old. The study shows that a significant amount of water predates the solar system; it originated in the Nebula — an interstellar cloud of dust from which the Sun and the planets were born.
This increases the likelihood of life being found on exoplanets orbiting other stars in the galaxy.
“By identifying the ancient heritage of Earth’s water, we can see that the way in which our solar system was formed will not be unique, and that exoplanets will form in environments with abundant water,” said Professor Tim Harries of the University of Exeter’s Physics and Astronomy Department, in a statement. “Consequently, it raises the possibility that some exoplanets could house the right conditions, and water resources, for life to evolve.”
Water is essential for life on Earth, and likewise, it’s a crucial factor for evaluating the chances of extra-terrestrial life on other planets. Scientists have found the evidence of water in some form throughout the space. They have found its frozen deposits on icy comets and moons, while the mineral samples obtained from meteorites, the Moon, and Mars also contained watery elements.
Comets and asteroids are among the most primitive objects in the universe so their ice can offer a better explanation for the ice that encircled the Sun back then. Scientists believed the Earth’s water came from the proto-planetary disc, or solar nebula, surrounding the Sun in early days after its birth. But they were unsure if the water was already existent in the Sun’s parental interstellar molecular cloud, or whether it came into being as a result of chemical reactions in the solar nebula.
“Why this is important? 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,” explained Carnegie Institution for Science’s Conel Alexander, who also contributed to the research.
“But if the early Solar System’s water was largely the result of local chemical processing during the Sun’s birth, then it is possible that the abundance of water varies considerably in forming planetary systems, which would obviously have implications for the potential for the emergence of life elsewhere.”
To figure stuff out, the research team created a model of the forming solar system by using ‘regular water’ ice containing hydrogen and ‘heavy water’ ice containing the isotope deuterium, which differs in the number of neutrons from hydrogen. The difference in masses between isotopes forms the basis of the differences in their behavior during chemical reactions. So the ratio of hydrogen to deuterium in water molecules can define the possible prevalent conditions under which they were formed.
The team stimulated a protoplanetary disk in which they removed all the deuterium from the interstellar ice to see if the system could generate heavy water from scratch and reach the ratios of deuterium to hydrogen that are found in comets, meteorite samples and Earth’s ocean water.
They discovered that the system could not do so, which means at least some of the water in our solar system came from the molecular cloud and predates the birth of the Sun.
“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.
This research leads us to the conclusion that, out of the estimated 11 billion exoplanets, some of them which are at just the right distance from their stars could have liquid water, and, possibly, life as well.