Superflares from the Sun may have allowed life to flourish on Earth

"Most investigators ignore galactic cosmic rays because they require specialized equipment, like particle accelerators," Kensei Kobayashi, a professor of chemistry at Yokohama National University in Japan and lead author of the study, said in the press statement. "I was fortunate enough to have access to several of them near our facilities."

The largest coronal mass ejection (CME) recorded in human history is the 1859 Carrington Event, which released the same amount of energy as 10 billion one-megaton atomic bombs. As Space.com points out, the superflares considered in the new paper dwarf this event and will have been hundreds to thousands of times more energetic.

Today, superflares are believed to erupt only once every 100 years or so. However, a 2016 study suggests that, during Earth's first 100 million years, superflares were much more common and occurred every three to 10 days.

Did solar superflares allow life to flourish on Earth

In order to simulate the role superflares played in the evolution of our atmosphere, the scientists combined carbon dioxide, molecular nitrogen, water, and different amounts of methane into mixtures of gases that were likely present in the Earth's early atmosphere.

They then shot the mixture with protons from a tandem accelerator, a type of small particle accelerator. At the same time, they shot another set of the same mixtures with simulated lightning to test the theory that lightning could have also triggered the required chemical reactions.

They found that both experiments triggered the production of amino acids and carboxylic acids, both of which are important building blocks for proteins.

However, the researchers found that their proton mixture only needed 0.5 methane concentration, whereas the lightning discharges needed 15 percent methane to produce those building blocks at detectable levels.

"And even at 15% methane, the production rate of the amino acids by lightning is a million times less than by protons," study co-author Vladimir Airapetian, an astrophysicist at NASA’s Goddard Space Flight Center, who also worked on the 2016 Nature Geosciences study, explained in the statement.

"During cold conditions you never have lightning, and early Earth was under a pretty faint sun," Airapetian continued. "That's not saying that it couldn't have come from lightning, but lightning seems less likely now, and solar particles seem more likely."