5–7 Billion Years From Now: The Red Giant Phase Begins
- The Sun, having depleted its hydrogen and helium reserves, begins expanding dramatically, turning into a red giant.
- It will grow to approximately 256 times its current size, significantly altering the solar system.
5 Million Years After the Red Giant Forms: Destruction of Inner Planets
- The red giant expands into the inner solar system.
- Mercury and Venus are engulfed, their orbits consumed by the Sun’s vast outer layers.
Planetary Changes on Earth: A Slow Death
- Carbon Dioxide Depletion
- Intense heat prevents the carbon cycle from functioning. Plants, which rely on carbon dioxide, begin to die.
- Oxygen Decline
- As plants vanish, oxygen levels plummet. Mammals and birds, which require high oxygen levels, are the next to perish.
- Survival of Microbial Life
- Insects succumb to the rising temperatures, leaving microbial life as the last form of Earthly existence.
- Tardigrades’ Final Stand
- Tardigrades, known for their resilience to extreme radiation and temperatures, survive until conditions become utterly inhospitable.
Earth’s Surface Transformation
- Temperatures exceed 2,400 K (2,130°C or 3,860°F), causing relentless storms, wind, and rain.
- Earth’s atmosphere dissipates, exposing the planet to the harshness of space.
- The surface is left covered with molten lava and metal oxides as the oceans evaporate.
- With no water, tectonic plate movement ceases, halting geological activity.
7.6 Billion Years From Now: Earth Engulfed
- The red giant reaches its maximum size, swallowing Earth and the Moon.
- The planet’s surface, now uninhabitable, melts into the Sun’s outer layers.
Formation of a New Habitable Zone
- The Sun’s expansion pushes the habitable zone outward, extending into the Kuiper Belt.
- Icy bodies like Triton (a moon of Neptune) and the dwarf planet Eris develop liquid water, potentially making them suitable for human colonization.
The Sun’s Ultimate Fate: A Black Dwarf
- Over the next quadrillion years, the Sun will shed its outer layers, first becoming a white dwarf and eventually cooling into a black dwarf.
- This cold, dense remnant will mark the end of the Sun’s life cycle, a faint echo of the once-vibrant star that powered the solar system.
Human Prospects Beyond Earth
- Advanced civilizations may relocate to the outer solar system, thriving on Triton, Eris, and other worlds rich with newly melted water.
- Beyond the Sun’s life, humanity may look to distant stars or new technologies to sustain life, keeping the story of Earth alive in memory and exploration.
This timeline serves as a stark reminder of Earth’s finite existence and humanity’s quest to find new frontiers amidst cosmic change.
