Even if humanity survives the overheating of the planet and if we don’t blow ourselves up with nuclear weapons, and if we can live through the super resistant bacteria and genetically engineered viruses, and if the rise of super intelligent A.I. and the alien war of 35000 AD doesn’t kill us, the Sun is still going to become a red giant and engulf Earth in a little over 6 billion years.
But before that, in about a billion years from now the Sun will grow brighter and evaporate Earth’s oceans.
So, how do we ensure human survival?
One approach is to move to another planet. A lot of people have suggested the idea of establishing colonies on other planets, so that in the event of a global disaster not all life from Earth would be wiped out.
Moving to another planet doesn’t seem like an entirely unreasonable goal, but it doesn’t solve the problem for life on Earth.
Another approach suggests moving the entire planet, how would we accomplish such a feat?
In 6.3 billion years, the Sun will be in its red giant stage and will be 2.2 times brighter than it is today. By that time, Earth will need to be at the same distance from the Sun as Mars to get about as much sunlight as Earth does today
To accomplish the great feat of moving the planet, two suggestions are to either use solar sails or use icy bodies from the outside solar system to accelerate Earth into a wider orbit.
Moving Earth can be done by changing the orbits of icy bodies in the distant solar system so they would pass close to Earth, transferring some of their energy to the planet. A million close passes would accelerate Earth into a wider orbit, but these close passes could be cataclysmic if we get it wrong.
Another less dangerous way to move the planet would be to use a giant solar sail. Solar sails are thin, mirror-like sails that are propelled by the pressure of sunlight. A solar sail could be deployed to float at a point where the pressure of solar radiation balances the sail between the gravitational pull of Earth, slowly pulling Earth out as the sun pushes the sail.
Moving Earth would require a sail nearly 20 times Earth’s diameter and would have to deployed about five times the distance of the moon from Earth.
A solar sail could be built in space using raw materials mined from a metal-rich asteroid. Nickel and iron from an asteroid could be fabricated into a massive 8-micron-thick mirror.
All of the plans to move Earth would potentially result in the orbit disruption of other planets. Planetary orbits are shaped by the gravitational pull of their neighbors, so moving the Earth would change the orbits of the other inner planets in unpredictable and potentially dangerous ways. Even if we had the capacity to move Earth, the event could send the inner solar system into chaos beyond what we could control.