It’s amazing to think that almost three-quarters of the Earth’s surface is water. Have you ever wondered how it got here? Some scientists have theorized water was brought to the planet when space rocks made of ice smashed into the surface well after the planet was formed. Other experts argue that water has been here since earth’s creation. But no one knows for certain.
A team of international scientists have discovered new evidence which supports the latter belief – that water has been a fundamental part of planet Earth from its beginning, sometime around 4.5 billion years ago. According to the earth scientist at the University of Glasgow who lead the research team, the data suggests the majority of the planet’s water came from water molecules stuck to the surface of dust particles which eventually accreted together to form Earth. Therefore, water was brought in during the planet’s initial formation. We were a wet planet from the very beginning.
The study involved the examination of Icelandic lava and volcanic rocks taken from an island off of the Canadian coast. The rocks came from ancient sources from beneath the planet’s surface which had remained untouched since the Earth’s formation. Scientists were able to look closely inside the rocks in order to detect chemical traces of water, including its hydrogen composition. They could do this by using an advanced instrument called an ion microprobe.
Researchers were also able to determine the traces of water had a chemical composition with very little deuterium (a hydrogen isotope sometimes referred to as heavy hydrogen) present. While deuterium can be connected to a variety of planetary bodies found in space, the amount found in this water indicates it was not carried here from somewhere else. A lot can be learned about the origins of the water found on any planet by looking at the ratio of deuterium to hydrogen found in core samples. This ratio can change over time, being mixed by shifting tectonic plates is one example, but the dust grains analyzed by researchers were retrieved from deep within the earth where they had remained unaltered and able to preserve the planet’s initial Deuterium-Hydrogen ratio.
The conclusion reached by researchers is that the water molecules were part of the dust which surrounded our sun, dust particles which accumulated to help form planet Earth, pushing back the clock on the origin of our planet’s water to when all the planets of our solar system were still forming.
The researchers do not rule out the possibility that some of the water covering 70 percent of the planet today could have arrived later however, the evidence suggests enough water was already here for life to have started earlier than previously thought. The researchers are hopeful their findings will be used by astronomers to help find and better understand the other planets within the universe that may also have water. The study was published in the journal Science.
Image courtesy of Wikimedia Commons user: Muns