Researchers revealed that life on our planet started after a huge cosmic collision. this event took place 4.4billion years ago.
Scientists had known for years that carbon-based life forms like human beings should have been impossible because the element carbon would have boiled away into space in the early ages of Earth.
But now experts from Rice University, Texas, believe that humanity, and all other life on our planet, are simply here by a fortunate twist of fate after Earth smashed into a small rogue planet a little later in cosmic time.
The team set out to explain why there is an abundance of carbon outside of the Earth’s core in “the mantle portion”.
Rajdeep Dasgupta, a petrologist from Rice University, said: “Even before this paper, we had published several studies that showed that even if carbon did not vaporise into space when the planet was largely molten, it would end up in the metallic core of our planet, because the iron-rich alloys there have a strong affinity for carbon.”
The research, published in Nature Geoscience, says that one third of the Earth’s mass is the planet’s core, which is mostly made up of iron.
The mantle accounts for the majority of the other two thirds while the crust and atmosphere make up just one per cent.
However, the researchers say that all of the Earth’s carbon, which is essential to all life, should have boiled away or got sucked into the molten core.
Lead author Yuan Li said: “One popular idea has been that volatile elements like carbon, sulphur, nitrogen and hydrogen were added after Earth’s core finished forming.
“Any of those elements that fell to Earth in meteorites and comets more than about 100 million years after the solar system formed could have avoided the intense heat of the magma ocean that covered Earth up to that point.
“The problem with that idea is that while it can account for the abundance of many of these elements, there are no known meteorites that would produce the ratio of volatile elements in the silicate portion of our planet”.
For this reason, the scientists began thinking about the idea that one of Earth’s neighbours collided into our planet, providing an abundance of carbon that was the basis for the beginning of life on the planet.
Dr Dasgupta continued: “We thought we definitely needed to break away from the conventional core composition of just iron and nickel and carbon.
“So we began exploring very sulphur-rich and silicon-rich alloys, in part because the core of Mars is thought to be sulphur-rich and the core of Mercury is thought to be relatively silicon-rich.
“It was a compositional spectrum that seemed relevant, if not for our own planet, then definitely in the scheme of all the terrestrial planetary bodies that we have in our solar system.
“One scenario that explains the carbon-to-sulphur ratio and carbon abundance is that an embryonic planet like Mercury, which had already formed a silicon-rich core, collided with and was absorbed by Earth.
“Because it’s a massive body, the dynamics could work in a way that the core of that planet would go directly to the core of our planet, and the carbon-rich mantle would mix with Earth’s mantle.”