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Before it became visible as the Pale Blue Dot, early Earth may have been aglow in orange, and this might have helped to make it habitable.

Scientists at the Virtual Planetary Laboratory, the NASA Astrobiology Institute (NAI) team based at the University of Washington, have developed a simulation of Earth during the Archaen era (3.8-2.5 billion years ago), with the atmosphere supporting an organic-rich and orange-colored haze that—shifting from previous haze studies— provided UV and temperature shielding to support the existence of life.

The paper, “The Pale Orange Dot: The Spectrum and Habitability of Hazy Archaen Earth,” was published in Astrobiology.

This Earth model builds on previous studies that speculate on the existence of an orange haze, but introduces the factors of climate, photochemistry, and fractal hazes. By better understanding Archaen Earth, scientists hope to increase their understanding of similarly hazy exoplanets and their potential habitability. “The Pale Orange Dot” was presented at the Annual Meeting of the Division of Planetary Sciences conference in November 2015, with a news release available from the University of Washington.

The study was supported in part by the NASA Astrobiology Institute, the NASA Early Career Collaboration Award, the NASA Postdoctoral Program, and the NASA Exobiology Program.