The first building blocks of life on Earth may have formed thanks to explosions from the Sun, according to a new NASA study.

A series of chemical experiments has shown how solar particles, colliding with gases in Earth’s early atmosphere, can form amino acids and carboxylic acids, the basic building blocks of proteins and organic life.

The findings were published in the journal Life.

To understand the origin of life, many scientists try to explain how amino acids, the raw materials from which proteins and all cellular life were formed, were formed.

The best-known hypothesis began in the late 1800s, when scientists developed the scenario that life might have started in a “warm little pond”: a soup of chemicals, created by lightning, heat and other energy sources, that could to mix in concentrated amounts forming organic molecules.

In 1953, Stanley Miller of the University of Chicago attempted to recreate these initial conditions in the laboratory.

Miller filled a sealed chamber with methane, ammonia, water and molecular hydrogen—gases believed to be prevalent in Earth’s early atmosphere—and repeatedly fired an electric spark to simulate the lightning effect.

A week later, Miller and his advisor Harold Urey, a graduate student at the University, analyzed the contents of the chamber and found that 20 different amino acids had formed.

“It was a big revelation,” said Vladimir Hayrapetian, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who co-authored the new work.

Looking for alternative sources of energy, some scientists pointed to shock waves from incoming meteorites. Others mentioned solar UV radiation.

Airapetian, using data from NASA’s Kepler mission, showed a new idea: energetic particles from our Sun.

Kepler observed distant stars at different stages of their life cycle, but its data provide hints about the Sun’s past.

In 2016, Airapetian published a study suggesting that during Earth’s first 100 million years, the Sun was about 30% dimmer.

But solar “superflares” – powerful explosions we see only once every 100 years or so today – used to erupt once every 3-10 days.

These superflares eject particles at nearly the speed of light that would regularly collide with the atmosphere, creating chemical reactions.