Water Came To Earth Aboard A Comet - Study
Scientists have long wondered how Earth came to be covered by 70 percent water - and a new study suggests that the answer may lie in asteroids and comets.
A study published in the journal Monthly Notices of the Royal Astronomical Society, describes water delivery via asteroids or comets is likely taking place in many other planetary systems, just as it happened on Earth, writes Nature World News.
According to conventional theory, water came to Earth when it was a dry, inhospitable world transported by icy comets and asteroids colliding with Earth - depositing water on the surface. Though, some scientists have said that in addition to these "wet" comets, Earth created the watery conditions from a series of geologic processes. Another theory concludes that such collisions would have made any existing water evaporate, and that surface water originated from carbonaceous chondrites, the most primitive kinds of meteorites.
However, these latest research findings add further support to the theory that water can be delivered to Earth-like planets via asteroids and comets - creating a suitable environment to foster 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.
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), writes Nature World News. This showed that a water-rich exo-asteroid was disrupted and eventually delivered the water it contained onto the star.
The team discovered that the asteroid was comparable in size to Ceres, the largest asteroid in the Solar System, measuring 600 miles (900 kilometers) across.
"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 integration of hydrogen and oxygen into the atmosphere. And large amounts of both of these elements were detected 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."
A vast amount of planetary bodies, including asteroids and comets, hold large quantities of water - a discovery that could aid in the search for other habitable worlds.