Earth's first atmosphere
Volcanoes exhale a thick shroud of carbon dioxide, nitrogen and steam — and no oxygen at all.
- When
- Known to
- ± 50 million years
- Era
- Hadean
As the magma ocean solidifies, dissolved gases escape to form a dense atmosphere of carbon dioxide, water vapour, nitrogen and sulphur compounds. There is essentially no free oxygen; anything breathing it would die within minutes. The greenhouse effect from all that carbon dioxide keeps the surface warm despite a Sun only about 70% as bright as today's — the resolution of what is called the faint young Sun paradox.