Solar System/Earth

Earth is the third planet of the Solar System. It is the basis and namesake of the units for measuring mass and radius *Earth mass* (Mearth) and *Earth radius* (Rearth).

# Name

Earth is the only planet in the Solar System not named after a god/goddess. Its name derives from Old English "eorthe" and "ertha", German "erde", meaning "ground".

# Current status

It is currently classified as a terran planet. Its surface has roughly 71% water, making the remaining 29% land.

# Future events

## Under 1 Gy

* **250 ky**: Lo'ihi is now a volcanic island.
* **300 ky**: WR 104 has likely exploded in a supernova. There is a miniscule chance that Earth has been hit by a gamma ray burst and depleted of life.
* **500 ky**: Multiple events:
	+ Earth has likely been hit by an asteroid of at least 1 km in diameter.
	+ Badlands National Park has been eroded and is now a flat piece of land.
* **2 My**: The Grand Canyon has widened due to erosion, and is now the Grand Valley.
* **180 My**: Earth's rotation period is now roughly 25 hours.
* **250 My**: All the continents have merged into a large supercontinent.
* **400 My**: The new supercontinent has dissolved back into multiple continents.
* **500 My**: The beginningof the end. The Sun is now a few percent more luminous than the present day. This damages the carbonate-silicate cycle. CO2 is absorbed into the rocks as carbonate, reducing carbon dioxide levels in the air. C3 photosynthesis is no longer possible, causing most plant life to die.
* **800 My**: Carbon dioxide levels have declined even further, rendering C4 photosynthesis invalid. The ozone layer is no longer recyclable, so now dangerous UV radiation can strike the surface of the Earth, killing not only all plant life, but most animal life as well.

## 1 Gy

* **1 Gy**: Earth has lost 27% of its oceans to the mantle, which has absorbed the oceans.
* **1.1 Gy**: Earth's surface temperature is now 47°C. This will trigger a runaway greenhouse effect that reduces all surface water on the planet to the poles, making it an oasis planet. It's still well possible that life can still exist on the poles, however it won't last long.
* **1.2 Gy**: All animal life and plant life on Earth has died, assuming they haven't adapted to low CO2 and high UV radiation.
* **1.3 Gy**: All eukrayotes have died, leaving only prokrayotes, again assuming there hasn't been significant adaptation.

## 2 Gy

* **2 Gy**: All of Earth's oceans have evaporated by now, making it a desert planet.
* **2.3 Gy**: Earth's magnetic field has now defunct. The atmosphere depletes, because solar wind is no longer being blocked be a magnetic field. Solar wind collides with the atmosphere, charging particles in the atmosphere so much that they completely escape into space.
* **2.8 Gy**: Earth's average surface temperature is now 147°C, and all life has died.

## 3 Gy

* **3 Gy**: Multiple events:
	+ The Moon's orbit is now so far away that Earth's axial tilt is now chaotic, making seasons extreme.
	+ There is a 1 in 3 million chance that Earth is ejected from the Solar System and placed into orbit around another star. Provided the conditions are exactly right, Earth may be placed back into the habitable zone.
* **3.3 Gy**: There is a miniscule chance that Mercury's orbit is displaced into a collision course with Earth.
* **3.5 Gy**: Earth's surface temperature is now 1130°C, hot enough to melt rock.

## 7 Gy

* **7.5 Gy**: Earth, along with Mars, is now tidally locked with the Sun.
* **7.8 Gy**: The Sun undergoes the first helium flash, causing Earth's surface temperature to rapidly drop.
* **7.88 Gy**: The Sun is now an asymptotic giant star, causing Earth's surface temperature to rise higher than ever before. It's well possible that Earth could fall into the Sun at this point.
* **7.9 Gy**: The Sun is now a white dwarf, causing Earth's surface temperature to rapidly drop to less than -250°C. Not much else happens at this point.