Eruptions from the Sun could have kickstarted life on Earth, a new study reveals.
A series of chemical experiments have shown that solar particles, colliding with gases in Earth’s early atmosphere, could have formed amino acids and carboxylic acids - the basic building blocks of proteins and organic life.
In 2009 NASA launched its Keplar mission to find other Earth-like planets that orbit other stars.
The mission observed far-off stars at different stages and revealed hints about our Sun’s past.
It brought around the idea that energetic particles from our Sun could have kickstarted the creation of the Earth.
They found that during the Earth’s first 100 million years, the Sun was likely about 30 per cent dimmer.
At this time powerful eruptions would happen once every three to 10 days.
This is much more frequent than today where we can only see them once every 100 years.
These eruptions caused super flares to regularly collide with our atmosphere.
With the presence of specific gases in the air, scientists suggest that these flares created chemical reactions which made the building blocks of life.
A soon as these findings were published, Dr Vladimir Airapetian, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and co-author of the study, was contacted by a professor of chemistry from the Japan's Yokohama National University.
Dr Airapetian said: “As soon as I published that paper, the team from the Yokohama National University from Japan contacted me.”
The professor of chemistry, Dr Kobayashi, was trying to understand how incoming particles from outside our solar system could have affected early Earth’s atmosphere.
Dr Kobayashi said: “Most investigators ignore galactic cosmic rays because they require specialised equipment, like particle accelerators.
"I was fortunate enough to have access to several of them near our facilities."
Minor tweaks to Kobayashi's experimental setup allowed Dr Airapatian to put his ideas to the test.
Together they created a mixture of gases that matched the Earth’s early atmosphere.
They combined carbon dioxide, molecular nitrogen, water and a variable amount of methane.
They then shot the gas mixtures with protons, which acted like the solar flares.
They also ignited them with spark discharges that acted as lightning.
As long as the methane proportion was over 0.5 per cent, the mixtures shot with the solar particles produced a detectable amount of amino acids and carboxylic acids.
The lightning however required around 15 per cent of methane before any amino acids formed.
The protons acting as solar particles also tended to produce more carboxylic acids, a precursor of amino acids, than those ignited by the lightning.
Dr Airapatian said: “And even at 15 per cent methane, the production rate of the amino acids by lightning is a million times less than by protons.”
The test thus showed that solar particles appear to be a more efficient energy source than lightning.
The team took inspiration from the idea of a “warm little pond” that was formed in the 1800s.
The theory suggests that life began by a pond made up of a mix of chemicals that were energised by lightening, heat and other energy sources. When mixed together, they formed organic molecules and created life.
In 1953, a scientist at the University of Chicago, Dr Stanley Miller, tried to recreate these conditions in a lab.
Dr Miller filled a closed chamber with methane, ammonia, water and molecular hydrogen – gases thought to be prevalent in Earth’s early atmosphere.
He then repeatedly ignited an electrical spark to simulate lightning.
A week later, Miller analysed the chamber’s contents and found that 20 different amino acids had formed.
Dr Airapetian said: “That was a big revelation. From the basic components of early Earth’s atmosphere, you can synthesise these complex organic molecules.”
Scientists however now believe that ammonia and methane were far less abundant, and that instead carbon dioxide and molecular nitrogen filled the air.
These gases require much more energy than lightning to break down, meaning that the solar flares are the likely source of energy that created life.
Dr Airapetian said “During cold conditions you never have lightning, and early Earth was under a pretty faint Sun.
“That's not saying that it couldn't have come from lightning, but lightning seems less likely now, and solar particles seems more likely.”
These experiments suggest that the active young Sun could have created the precursors of life more easily, and perhaps earlier, than previously assumed.
The study was published in the journal Life.
