5 to 7 Billion Years from Now: The Red Giant Phase
- Our sun exhausts its hydrogen and helium supplies: The sun will swell into a red giant, growing to 256 times its current size as its core collapses and outer layers expand.
- Mercury and Venus engulfed: The sun’s expansion will swallow the inner planets. Earth will experience intense heat as it teeters on the edge of destruction.
5 Million Years into the Red Giant Phase
- Carbon dioxide depletion: The extreme heat will prevent carbon dioxide from being replenished in the atmosphere. This marks the beginning of Earth’s biosphere’s demise.
- Plant extinction: The lack of carbon dioxide will kill off plants, ceasing oxygen production and triggering a catastrophic collapse in ecosystems.
- Animal extinction: Mammals, birds, and other oxygen-dependent life forms will perish. Insects and simpler life forms with low oxygen requirements will survive briefly.
Final Survivors: Microbial Life and Tardigrades
- Microbial resilience: As conditions worsen, only microbes adapted to extreme environments will endure.
- Tardigrades persist: These nearly indestructible creatures will be the last to survive the rising radiation and heat.
Planetary Transformation
- Atmosphere loss: The atmosphere will be stripped away due to relentless solar radiation.
- Surface conditions: Earth will become a barren, metal-oxide-covered wasteland as temperatures exceed 2,400 K (2,130 °C or 3,860 °F).
- Ocean evaporation: All water will boil away, leaving a planet with lava oceans.
- End of tectonic activity: Without water to lubricate tectonic plates, Earth’s geological activity will halt.
7.6 Billion Years from Now: Earth’s End
- Engulfment by the red giant: Earth and the moon will be consumed by the expanding sun.
- A new habitable zone: The habitable zone of the solar system will shift outward into the Kuiper Belt, beyond Neptune. Icy bodies like Triton and Eris could host liquid water, making them potential sites for human colonies.
Far Future: The Fate of the Sun
- 1 Quadrillion Years from Now: The sun, after exhausting its nuclear fuel, will cool and shrink into a black dwarf—a dark, cold remnant of its former self, no longer capable of sustaining life or warmth.
The New Frontier
As Earth meets its fiery end, humans may adapt by colonizing the outer solar system:
- Neptune’s Triton: With its subsurface ocean, this moon could be a haven for life.
- Eris and Kuiper Belt objects: Icy bodies warmed by the shifting habitable zone could sustain human settlements.
Earth’s death is an eventual certainty, but the ingenuity of humanity may ensure survival in the cosmos, even in the face of the sun’s inevitable demise.
