The Sun Was Too Faint for Earth to Survive

3.5 billion years ago the Sun was about 30% fainter than it is today. Every climate model says early Earth should have frozen solid — yet the rocks from that era are full of liquid water and the earliest signs of life. Fifty years after Carl Sagan named it, the Faint Young Sun Paradox is still open. Here's why it refuses to die — and why it quietly undermines our confidence about which other worlds could be alive.

CHAPTERS
0:00 Cold open
1:03 The Dimmer Star
3:09 The Earth That Refused to Freeze
5:22 The Greenhouse Rescue
7:46 The Open Verdict

Sources & further reading:
- Sagan, C. & Mullen, G. (1972). "Earth and Mars: Evolution of Atmospheres and Surface Temperatures." Science 177, 52.
- Feulner, G. (2012). "The faint young Sun problem." Reviews of Geophysics 50, RG2006.
- Charnay, B. et al. (2020). "Faint young Sun problem revisited." Space Science Reviews.
- Standard solar model — Bahcall et al.

This video uses AI-assisted narration and AI-generated illustrated backgrounds. Researched, written, and produced by a human.

#science #space #earth #astronomy #strangealmanac

Photo credits:
• The Sun by the Atmospheric Imaging Assembly of NASA's Solar Dynamics Observatory - 20100819.jpg — NASA/SDO (AIA), Public domain (Wikimedia Commons)
• The Earth seen from Apollo 17.jpg — NASA/Apollo 17 crew; taken by either Harrison Schmitt or Ron Evans, Public domain (Wikimedia Commons)
• Carl Sagan Planetary Society.JPG — NASA/JPL, Public domain (Wikimedia Commons)
• Titan in true color.jpg — NASA/JPL-Caltech/Space Science Institute, Public domain (Wikimedia Commons)
• Kepler186f-ArtistConcept-20140417.jpg — NASA Ames/SETI Institute/JPL-Caltech, Public domain (Wikimedia Commons)
• Black-band ironstone (aka).jpg — André Karwath aka Aka, CC BY-SA 2.5 (Wikimedia Commons)
• Pillow basalt crop l.jpg — National Oceanic and Atmospheric Administration, Public domain (Wikimedia Commons)
• Stromatolites in Sharkbay.jpg — Paul Harrison, CC BY-SA 3.0 (Wikimedia Commons)
• SideriteBresil2.jpg — Didier Descouens, CC BY-SA 4.0 (Wikimedia Commons)

Видео The Sun Was Too Faint for Earth to Survive канала Strange Almanac