What does the future have in store?

I don't mean the future history of mankind here. Human activity and behavior are just too chaotic to create a future timeline for mankind. What I want to discuss is what will happen to the Earth, the Sun, the Solar System, the Milky Way galaxy, and the Universe.

Let's start with our source of energy, the Sun. At this point in time, half of the hydrogen in the core of our Sun has been consumed. The Sun's energy output rises 1% every 110 million years, so in 3 billion years, the Sun will be 33% more luminous. This increase will fry us but good. Forget about global warming. This will be global frying. The oceans will evaporate in a few billion years. The current rate of loss is roughly one meter of ocean per billion years. But, this will accelerate in the future because of this gradual warming of the atmosphere. It's safe to predict that most life will be gone by 1 billion years when the Sun will be 10% brighter.

One thing that will happen is the gradual drop in carbon dioxide because the heat will cause the gas to form solid carbonates, and in 600 million years the CO2 concentration will drop below the level needed for photosynthesis. The trees and plants will die; although, it's possible that they could adapt and survive for up to 1.5 billion years.

The worst fate for the Earth is that it would enter a severe greenhouse era that would end up boiling the oceans into the atmosphere and then heating up to hundreds of degrees like Venus. That could happen in 2 billion years or so.

The only way that we could avoid all of this is to find a way to move the Earth into an orbit further away from the Sun. I don't know how we could do that trick. I remember a British science fiction TV series called 'Space:1999' where spent nuclear fuel stored on the Moon exploded sending the moon out of orbit and off to wander the universe with the people who were stuck on it. Maybe we could use that technique to move the Earth. We sure as hell have enough nuclear bombs to do it.

Another possible way would be to park a large asteroid close to the Earth and allow it to gradually pull the Earth's orbit further from the Sun. This idea would require a long time, possibly a million years to be effective.

There are some who reason that the gradual rise in CO2 will cease and be reversed in the future and this could plunge us into an ice age in about 5000 years. The other strange thing that may precipitate an ice age is the slow loss of the moon with its resultant change in the Earth's tilt stability. Then, there is the gradual change in the continents because of tectonics. North America is slowly moving to Africa and South America will wrap around the southern tip of Africa to form a supercontinent. This process will take a long time, about 250 million years by some estimates. The bottom line is that we will all end up in Africa from whence we came.

The worse thing that could happen is if the Earth's core stops rotating and we lose our magnetic field. That would result in the Earth's atmosphere being blown away by the solar wind.

Ultimately, when the Sun uses up all its hydrogen and begins to burn helium, it will grow into a red giant and swallow the Earth. However, the red giant phase won't happen for at least another 4-5 billion years and the Earth won't be absorbed until 7.5 billion years from now.

The other thing to keep in mind is that the solar system is not stable when you talk about a billion years. The Moon, for example, will slowly drift away, making the Earth's spin unstable. The Earth could also be affected by changes in the orbits of the gas giants like Jupiter; although, they are large enough to stay in stable orbits.

Another possibility is the Mercury-Jupiter 1:1 perihelion-precession resonance. This big term means that Mercury is linked to Jupiter gravitationally and changes its orbit 1.5 degrees every 1000 years. Eventually, over a billion years or so, Mercury will be knocked off course and either be thrown out of the solar system or driven into a collision with either Venus or Earth. This is another reason why we might want to move the Earth's orbit further out from the Sun; although, we will have to avoid getting near the asteroid belt.

If humans survive this they will still face the collision of Andromeda with our Milk Way galaxy in 4 or so billion years. Then there is the expansion of the universe that will eventually freeze everything in trillions of years from now.
Personally, I don't think it matters right now. However, it is fun to speculate.

Thanks for reading.