The Purple Earth and Methane Skies
Travel back to the Archean Eon, where purple microbes and orange smog created a truly alien home world.
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A thirty percent dimmer sun and thick methane haze once turned Earth's sky a permanent orange.
Early oceans appeared purple because retinal-based microbes absorbed green and yellow light before chlorophyll evolved.
Methane levels hundreds of times higher than today acted as a thermal blanket to prevent global freezing.
The moon was closer to Earth, creating massive lunar tides that thundered against iron-rich tea-colored oceans.
Cyanobacteria triggered a global ice age by producing oxygen that destroyed the planet's warming methane layer.
The human eye uses rhodopsin proteins repurposed from ancient purple microbes that dominated the early Earth.
- 01Intro1 min
- 02The Orange Horizon3 min
- 03The Faint Young Sun and the Methane Blanket4 min
- 04The Purple Earth Hypothesis4 min
- 05The Green Coup4 min
- 06The Ghost of a Purple World4 min
- 07Outro1 min
- Early evolution of purple retinal pigments on Earth and implications for exoplanet biosignatures
- The Archean atmosphere - PMC
- The Archean Eon - Forces of Change - Smithsonian Institution
- Was Life on the Early Earth Purple? | News | Astrobiology
- Purple Earth hypothesis
- [1311.1145] Characterizing the purple Earth: Modelling the globally-integrated spectral variability of the Archean Earth
- CHARACTERIZING THE PURPLE EARTH: MODELING THE GLOBALLY INTEGRATED SPECTRAL VARIABILITY OF THE ARCHEAN EARTH
- Purple is the new green: biopigments and spectra of Earth-like purple worlds
- When The Earth Was Purple
- Flying Purple People Eater | by Brian Koberlein
- Anoxygenic photosynthesis and the delayed oxygenation of Earth’s atmosphere | Nature Communications
- The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth
- Organic Haze as a Biosignature in Anoxic Earth-like Atmospheres
- Exploring the faint young Sun problem and the possible climates of the Archean Earth with a 3-D GCM
- Biological regulation of atmospheric chemistry en route to planetary oxygenation | PNAS
- [2006.06265] Is the faint young Sun problem for Earth solved?
- Pale Orange Dots: The Impact of Organic Haze on the Habitability and Detectability of Earthlike Exoplanets - IOPscience
- Evolution of the Archean Atmosphere
- Early evolution of purple retinal pigments on Earth and implications for exoplanet biosignatures
- The pale orange dot: the spectrum and habitability of hazy Archean Earth - University of St Andrews Research Portal
- Co-evolution of primitive methane-cycling ecosystems and early Earth’s atmosphere and climate
- Effects of primitive photosynthesis on Earth’s early climate system | Nature Geoscience
- Early Earth, the Pale Orange Dot, May Have Been Habitable | News | Astrobiology
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