Life In Outer Space? Early Earth's Haze Gives Clues On Habitability Elsewhere In Space

Researchers found that a pale orange haze around a distant planet could indicate the planet is probably habitable or could hold signs of life, according to a study at the University of Washington.

The orange haziness around the distant planet is almost identical to the one that once surrounded the earth while it was still young, according to the researchers. The earth is often used as a model to study features and characteristics from exoplanets, which could be potential clues for life and habitability on other planets.

"Hazy worlds seem common both in our solar system and in the population of exoplanets we've characterized so far," Giada Arney, lead author of the study, said in a news release. "Thinking about Earth with a global haze allows us to put our home planet into the context of these other worlds, and in this case, the haze may even be a sign of life itself."

The researchers chose to study the earth during its Archean era, two and a half billion years ago, since it is "the most alien planet we have geochemical data for," according to Arney.

The pale orange haze that surrounded the early earth most likely came from light that was pouring down on methane molecules, and an atmosphere with organic compounds of hydrogen and carbon. The haze that was found on the exoplanet would have reduced the planet's surface temperature.

"Giada's work shows that the haze could have intertwined with life in more ways than we previously suspected," Shawn Domagal-Goldman, co-author of the study from the NASA Goddard Space Flight Center in Greenbelt, Maryland.

The presence of haze on the exoplanet could have been formed abiotic (physically) or from non-living materials, according to the researchers.

"Organic haze might be a novel type of biosignature. However, we know these hazes can also form without life on worlds like Saturn's moon Titan," said Arney. "We are working to come up with more ways to distinguish biological hazes from abiotic ones."

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