Scientists have long wondered how our Blue Planet came to be covered by 70 percent water. Now a new study offers fresh evidence for how water reached Earth, finding that asteroids and comets are likely rich in water.
Described in the journal Monthly Notices of the Royal Astronomical Society, water delivery via asteroids or comets is likely taking place in many other planetary systems, just as it happened on Earth.
According to conventional theory, our dry, inhospitable world quenched its thirst for water when icy comets and asteroids from the far reaches of the solar system collided with Earth, depositing water on the surface. Though, some scientists have said that in addition to these "wet" comets, Earth actually made its own water from within from a series of geologic processes. Others claim that such collisions would have made any water evaporate, and that surface water actually came from carbonaceous chondrites, the most primitive kinds of meteorites.
Nonetheless, these latest research findings add further support to the theory that water can be delivered to Earth-like planets via asteroids and comets to create a suitable environment for the formation of life.
"Our research has found that, rather than being unique, water-rich asteroids similar to those found in our Solar System appear to be frequent. Accordingly, many planets may have contained a volume of water, comparable to that contained in the Earth," lead researcher Dr. Roberto Raddi, of the University of Warwick's Astronomy and Astrophysics Group, said in a press release.
"It is believed that the Earth was initially dry, but our research strongly supports the view that the oceans we have today were created as a result of impacts by water-rich comets or asteroids," he added. (Scroll to read on...)
In observations obtained at the William Herschel Telescope in the Canary Islands, the University of Warwick astronomers found a large quantity of hydrogen and oxygen in the atmosphere of a white dwarf (known as SDSS J1242+5226). This unique find provided evidence that a water-rich exo-asteroid was disrupted and eventually delivered the water it contained onto the star.
The asteroid, the team discovered, was comparable in size to Ceres - at 900 kilometers (~600 miles) across, the largest asteroid in the Solar System.
"The amount of water found SDSS J1242+5226 is equivalent to 30-35% of the oceans on Earth," Raddi explained.
The impact of water-rich asteroids or comets onto a planet or white dwarf results in the mixing of hydrogen and oxygen into the atmosphere. Both elements were detected in large amounts in SDSS J1242+5226.
"Oxygen, which is a relatively heavy element, will sink deep down over time, and hence a while after the disruption event is over, it will no longer be visible," said co-author Professor Boris Gänsicke.
"In contrast," he continued, "hydrogen is the lightest element; it will always remain floating near the surface of the white dwarf where it can easily be detected. There are many white dwarfs that hold large amounts of hydrogen in their atmospheres, and this new study suggests that this is evidence that water-rich asteroids or comets are common around other stars than the Sun."
The results of this study should really come as no surprise, not just because they add to an already popular theory, but also because NASA recently announced that there is actually a TON of water in our solar system and beyond. So it seems that numerous planetary bodies, including asteroids and comets, contain large amounts of water - a realization that could perhaps help in humanity's search for other habitable worlds.
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