While we may not be around to see the day, the estimates are a lot sooner than experts had previously predicted.
The Sun exists by burning hydrogen atoms into helium atoms at its core.
The giant ball of fire at the centre of our solar system burns through 600 million tonnes of hydrogen every second.
For every billion years that it burns hydrogen, the sun becomes about 10 percent brighter.
While that does not seem a significant increase, experts believe it could be disastrous for life on Earth.
Jillian Scudder, an astrophysicist at the University of Sussex, said: “The predictions for what exactly will happen to Earth as the Sun brightens over the next billion years are pretty uncertain.
“But the general gist is that the increasing heat from the sun will cause more water to evaporate off the surface, and be held in the atmosphere instead.
“The water then acts as a greenhouse gas, which traps more incoming heat, which speeds up the evaporation.”
The energy from the sun will continue to bombard Earth’s atmosphere and “split apart the molecules and allow the water to escape as hydrogen and oxygen, eventually bleeding Earth dry of water.”
In 3.5 billion years, the sun would shine about 35 percent brighter which would be enough to turn our planet into a dry, barren wasteland – much like Venus.
Then, in four or five billion years, the sun will have burned through its helium reserves.
At this point it will begin to burn helium, leading to a rapid expansion of the sun which will consume the planets surrounding it.
Ms Scudder said: “Once hydrogen has stopped burning in the core of the sun, the star has formally left the main sequence and can be considered a red giant.
“It will then spend about a billion years expanding and burning helium in its core, with a shell around it where hydrogen is still able to fuse into helium.”