Earth remained molten for yrs before its formation

NEW YORK: It's a research which sheds new light on the early formation of Earth -- our planet remained molten for tens of millions of years before it cooled slower.

A team of scientists in the United States has carried out the research and found the surface of terrestrial planets like Earth and Mars had remained molten for millions of years before their formation, the 'ScienceDaily' reported on Sunday.

According to the researchers from NASA's Johnson Space Centre and the Lunar and Planetary Institute and University of California, Davis, the findings reveal the early histories of the inner planets in the solar system are complex and involve processes no longer observed.

Evidence of these processes has been preserved in Mars while it has been erased in the case of Earth. So, Mars is the best opportunity to understand how Earth formed, according to the team.

"The formation of the solar system can be dated quite accurately to 4,567,000,000 years ago," lead researcher Qing Zhu Yin, an Assistant Professor at University of California- Davis was quoted as saying.

"Mars' metallic core formed a few million years after that. The persistence of a magma ocean on Mars for over 100 million years is surprisingly long. It implies that at the time, Mars must have had a thick enough atmosphere to insulate the planet and slow down cooling," Yin said.

According to the scientists, the early crust formation alone cannot account for the slow cooling magma ocean seen in large planets. This new evidence instead implies that Mars, at one time, had a primitive atmosphere that acted as insulator.

"The primitive atmosphere was composed mostly of hydrogen left over from accretion into a rocky planet, but was removed, probably by impacts, about 100 million years after the planet formed," said another researcher.

In fact, they performed precise measurements of neodymium isotope compositions of nine rare Martian meteorites called shergottites using mass spectrometers at JSC and UCD before coming to the conclusion.

"These rocks were lavas that were made by melting deep in Mars and then erupted on the surface. They were delivered to Earth as meteorites following impacts on Mars that exhumed them and launched them into space.

"We expected to find that their sources all formed at the same time. But what we found instead was that the shergottite sources formed at two different times.

"The oldest formed at 35 million years after the solar system began to condense from ice and dust into large planets about 4,567 million years ago. The youngest formed about 110 million years after the solar system began to condense," said the researcher.