YEARS FROM NOW: 1,000,000,000
The Sun's luminosity has increased by 10 percent, causing Earth's surface temperatures to reach an average
of ~320 K (47 °C, 116 °F). The atmosphere will become a "moist greenhouse", resulting in a runaway evaporation of
the oceans. Pockets of water may still be present at the poles, allowing abodes for simple life.
Earth's surface temperature, even at the poles, reaches an average of ~422 K (149 °C; 300 °F). At this
point, life, now reduced to unicellular colonies in isolated, scattered microenvironments such as
high-altitude lakes or subsurface caves, will completely die out.
The amount of water vapour in the lower atmosphere increases to 40%. This, combined with the luminosity of
the Sun reaching roughly 35–40% more than its present-day value, will result in Earth's atmosphere heating up and the
surface temperature skyrocketing to roughly 1,600 K (1,330 °C; 2,420 °F), hot enough to melt surface rock.
This essentially will make the planet much like how Venus is today.
The Earth and Moon are very likely destroyed by falling into the Sun, just before the Sun reaches the tip of
its red giant phase and its maximum radius of 256 times the present day value. Before the final collision, the Moon possibly
spirals below Earth's Roche limit, breaking into a ring of debris, most of which falls to the Earth's surface.
