As a result of the Sun having more helium and less hydrogen left, it is expected to gradually get brighter, and larger - somewhere around 500-1000 million years from now, it will probably get too hot for any life to survive on planet Earth. That is, unless we do something about that.
4 billion years ago
By hot zone, I assume you mean out of the habitable or Goldilocks zone. Estimates vary, but in all likely hood changes will become noticeable in about a billion years, and severe in three billion years.
13.5 billion years
Yes, in a few billion years.
Maybe there will be flying cars
It didn't happen. There was no 5 billion years ago. Just think about it; it doesn't make any amount of sense whatsoever.
This will probably never happen. Earth will most likely be destroyed in about 5 billion years when the sun runs out of hydrogen in its core and expands.
No. In about 5 billion years the sun will expand and will likely consume Earth.
Three billion years.
in a few billion years time the sun is go to melt it.
our sun will live for another 4.5 billion years
Four billion years from now, our galaxy, the Milky Way, will collide with our large spiraled neighbor, Andromeda.