How to keep the Earth habitable when the sun dies

In approximately one billion years, the sun will exhaust its fuel and swell into a red giant, incinerating Earth's oceans and atmosphere. The sun will then collapse into a dim white dwarf, extinguishing all light in the solar system. In a trillion years, star formation in the galaxy will cease, plunging everything into darkness.

However, there is a possible path for life to endure this cosmic transformation—without leaving Earth. The key is to develop protective measures. One approach involves constructing a massive sunshade at the Lagrange point 1, where the gravitational pull of the sun and Earth balance. To reduce the sunshade's size, a long cable could be anchored to the moon, with a weight attached to it.

Mining 40% of the dwarf planet Ceres could create a carbon tether stretching 2 million kilometers, while 0.01% of the moon's mass could produce a sunshade spanning 350,000 kilometers. This would block the sun's rays, providing artificial sunlight from the gas giants' hydrogen and helium reserves. If Earth is engulfed by the red giant, another solution is to gradually relocate it using an asteroid's gravitational pull.

Alternatively, firing a particle beam from Jupiter could achieve the same effect. Earth's tectonic activity, responsible for recycling nutrients necessary for life, would eventually cease. To maintain it, antimatter could be produced and released into Earth's core, causing its annihilation and generating heat. Regularly firing a beam of oxygen past Earth could also preserve its tectonic activity.

Should our galaxy collide with Andromeda in 4.5 billion years, a beam of hydrogen could be shot above or below the sun to guide the solar system out of harm's way. Although leaving the solar system might seem more appealing, building these safeguards would allow Earth to enjoy a comfortable environment for a staggering 9.1 quadrillion years, even as the sun eventually fades.