Earth's weak magnetic field helped Sun to steal water from planet's early atmosphere

Washington, March 5 (ANI): Scientists have discovered that the Earth's magnetic field 3.5 billion years ago was only half as strong as it is today, and that this weakness, coupled with a strong wind of energetic particles from the young Sun, likely stripped water from the early Earth's atmosphere.

The findings, by researchers at the University of Rochester, US, suggest that the magnetopause-the boundary where the Earth's magnetic field successfully deflects the Sun's incoming solar wind-was only half the distance from Earth it is today.

"With a weak magnetosphere and a rapid-rotating young Sun, the Earth was likely receiving as many solar protons on an average day as we get today during a severe solar storm," said John Tarduno, a geophysicist at the University of Rochester and lead author of the study.

"That means the particles streaming out of the Sun were much more likely to reach Earth. It's very likely the solar wind was removing volatile molecules, like hydrogen, from the atmosphere at a much greater rate than we're losing them today," he said.

According to Tarduno, the loss of hydrogen implies a loss of water as well, meaning there may be much less water on Earth today than in its infancy.

To find the strength of the ancient magnetic field, Tarduno and his colleagues from the University of KwaZulu-Natal visited sites in Africa that were known to contain rocks in excess of 3 billion years of age.

Tarduno picked out the best preserved grains of feldspar and quartz out of 3.5 billion-year-old dacite outcroppings in South Africa.

Once he isolated the ideal crystals, Tarduno used a device called a superconducting quantum interface device, or SQUID magnetometer.

Using the new magnetometer, the researchers were able to confirm that the 3.5 billion-year-old silicate crystals had recorded a field much too strong to be induced by the solar wind-atmosphere interaction, and so must have been generated by Earth's core.

"We needed to understand how much solar wind that magnetic field was deflecting because that would tell us what was probably happening to Earth's atmosphere," said Tarduno.

The solar wind can strip away a planet's atmosphere and bathe its surface in lethal radiation.

To discover what kind of solar wind the Earth had to contend with, Tarduno employed the help of Eric Mamajek, assistant professor of physics and astronomy at the University of Rochester.

"We estimate the solar wind at that time was a couple of orders of magnitude stronger," he said.

The smaller magnetopause allowed the solar wind to strip away more water vapor from the early Earth. (ANI)