Space & the universe
The Purple Earth and Methane Skies
19 min
Travel back to the Archean Eon, where purple microbes and orange smog created a truly alien home world.
Listen on the app, request early access:
Show notes
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.
In this episode
- 1Intro1 min
- 2The Orange Horizon3 min
- 3The Faint Young Sun and the Methane Blanket4 min
- 4The Purple Earth Hypothesis4 min
- 5The Green Coup4 min
- 6The Ghost of a Purple World4 min
- 7Outro1 min
Sources
- 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
Fylom generates episodes like this on any topic you're curious about.
Fylom episodes are researched and written by AI. Automated checks help catch inaccuracies, but episodes aren't reviewed by a human and AI can still get things wrong. Treat them as a starting point, not a source of record — more in our accuracy disclaimer.