Scientists call it the Faint Young Sun Paradox. Around four billion years ago, the sun’s brightness was about three-quarters of what we see today. Earth should have looked more like a ball of ice. But instead, evidence points to a warmer world with liquid water.
A team of scientists from NASA believes solar storms may be the answer. While the sun was much fainter, scientists believe solar storms were occurring with a much higher frequency than we see today.
Using NASA’s Kepler spacecraft, the team of scientists looked at stars that resembled our sun a few million years after it formed. The data showed superflares from these stars were much more common then than they are now. Today, superflares occur maybe once every 100 years. Back then? Up to 10 times a day.
Did You Know: The same storms NASA believes helped foster life on Earth is believed to be responsible for stripping much of Mars’ magnetic field away. Without it, Mars atmosphere was lost to space and the surface turned into the desolate one we see today.
Most of us never even know we are hit by solar flares. Those living near the poles can see the action as breathtaking auroras. If we could travel back in time, we would see colorful auroras all the way down to South Carolina according to Vladimir Airapetian, lead author of the new research and a solar scientist at NASA’s Goddard Space Flight Center.
“And as the particles from the space weather traveled down the magnetic field lines, they would have slammed into abundant nitrogen molecules in the atmosphere. Changing the atmosphere’s chemistry turns out to have made all the difference for life on Earth,” Airapetian added.
Four billion years ago, 90% of the atmosphere was molecular nitrogen. That’s up from the 78% we see today. When superflares interacted with Earth’s atmosphere, the molecular nitrogen split into individual nitrogen atoms. These atoms then smashed into carbon dioxide and split them into carbon monoxide and oxygen. I’ll let NASA take it from here.
The free-floating nitrogen and oxygen combined into nitrous oxide, which is a powerful greenhouse gas. When it comes to warming the atmosphere, nitrous oxide is some 300 times more powerful than carbon dioxide. The teams’ calculations show that if the early atmosphere housed less than one percent as much nitrous oxide as it did carbon dioxide, it would warm the planet enough for liquid water to exist.
This newly discovered constant influx of solar particles to early Earth may have done more than just warm the atmosphere, it may also have provided the energy needed to make complex chemicals. In a planet scattered evenly with simple molecules, it takes a huge amount of incoming energy to create the complex molecules such as RNA and DNA that eventually seeded life.
The new research sheds light on the history of our planet, but it can also help our search for other habitable worlds. It’s not enough to find a world around the same size or roughly the same orbit as Earth.
Scientists from many fields are coming together to “create a robust description of what the early days of our home planet looked like – and where life might exist elsewhere,” says William Danchi, co-author of the paper. “We want to gather all this information together, how close a planet is to the star, how energetic the star is, how strong the planet’s magnetosphere is in order to help search for habitable planets around stars near our own and throughout the galaxy.”