Tuesday, August 5, 2025

Will the Earth ever end?

 Yes, everything that has a beginning has an end.

The Earth, our home planet, is no exception.

The most likely scenario for its demise will be during the end of the main sequence for the Sun, in 7.88 billion years, where it has expended its hydrogen fuel and can no longer maintain hydrostatic equilibrium. It grows in volume exponentially to become a Red Giant. This will likely consume the Earth (and the Moon) utterly, they will become part of the Sun and no trace or evidence of its existence will remain.

If the eventual radius of the Sun does not exceed 150,000,000 km (1 AU), then the Earth will just get a front row seat of the helium flash, with the Sun filling the sky and surface temperatures exceeding those that boil carbon, it becomes vapour and part of the Sun’s photosphere.

It’s worth noting that no living things will perish at this time, as the Sun is increasing in luminosity and temperature by around 1% every 100 million years. So a billion years from now, and 6.8 billion before the Red Giant phase, the surface temperature on Earth will not support liquid water, the oceans will boil away, and all life as we know it will cease to exist.

Mars will survive the clutches of the expanded Sun, but have a surface temperature similar to Mercury now. Interestingly, the moons of Jupiter and/or Saturn might be hospitable (in purely a temperature sense) and allow liquid water on their surfaces.

If this fate, of the Earth becoming inhospitable to life in around a billion years, distresses you (in a philanthropic sense, as you’ll be long gone) then it shouldn’t.

This is what a human ancestor looked like 1 billion years ago:

No, not the dude next to the pick-up (he came along a little later), the green slime - Cyanobacteria - on the water.

These steps are not to scale, we have only been humanoids for around 4 million years, and only strictly human for 160,000 years:

So you can imagine, regarding how evolutionary development has sped up over time, what our descendants might look like in another 1 billion years. Or rather, you can’t imagine, but you get the idea.

Even without the exponential acceleration of our evolution allowed for by technology, and the unimaginable forms of meta-humans in just one thousand years, our descendants will not be anything vaguely resembling humanity by the time the Earth gets too hot to harbour life.

So the Earth will end, but it’s highly unlikely that what we become in the future will end with it. If we don’t manage to at least populate our solar system or build space habitats by then, it will be the worst case of under-achieving the Universe has seen since the Kjorg of Andromeda were gifted omniscience by an ancient pure energy culture and the chance to sublime, and decided to drink cocktails on their favourite beach planet instead.