The Key to Life on Earth May Have Been Projectile Sun Barf

These solar storms can inform the search for alien life.

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Jun 12 2016, 10:06pm

2012 coronal mass ejection. Image: NASA Goddard Space Flight Center

As we all know, the Sun is a real mensch. Without it, Earth would be a sad frozen husk devoid of life and light, which sounds a lot less interesting than being a lush ocean world that has yielded dinosaurs, dire wolves, and whatever this thing is.

That said, our star wasn't always as energetic and nourishing as it is today, which has led to longstanding debate over how it managed to seed life on our planet in its infancy some four billion years ago.

"Back then, Earth received only about 70 percent of the energy from the sun than it does today," said Vladimir Airapetian, a solar scientist at NASA's Goddard Space Flight Center, in a statement. "That means Earth should have been an icy ball. Instead, geological evidence says it was a warm globe with liquid water. We call this the Faint Young Sun Paradox."

Recently, Airapetian and his colleagues published a compelling explanation for this paradox in Nature Geoscience, which is outlined in this new NASA Goddard video. According to the team, the secret ingredient for life on our planet may have been the intense solar storms that erupted on the Sun during its early years.

"Our new research shows that solar storms could have been central to warming Earth," Airapetian said.

Though the Sun wasn't at full wattage four billion years ago, scientists think it was much more tempestuous than it is today. Judging by young Sunlike stars studied by the Kepler space observatory, the Sun likely belched out stellar explosions called superflares several times a day back then. While the Sun is still prone to spewing out projectile star stuff, it has taken it down a notch as the eons have rolled by, and now only indulges in superflares at a rate of once a century on average.

Imagine, then, an infant Earth bombarded with solar radiation from a trigger-happy star. Scientists think that all that energy might have created the right conditions for greenhouse gases like nitrous oxide to form, as well as complex organic molecules like hydrogen cyanide, which are essential for life. As an aesthetic bonus, it would also have sparked some fairly epic light shows in Earth's early skies.

"Our calculations show that you would have regularly seen auroras all the way down in South Carolina," said Airapetian.

Understanding the role these storms played in the origins of life could help scientists narrow down the search for alien organisms on distant worlds, in addition to contextualizing how it arose on our own.

"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," said William Danchi, a principal investigator at NASA Goddard and co-author on the Nature Geoscience paper.

"This work includes scientists from many fields—those who study the sun, the stars, the planets, chemistry and biology. Working together we can create a robust description of what the early days of our home planet looked like, and where life might exist elsewhere."

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