[Titanscape (OP)]

Can we calculate the year when the sun explodes and engulfs the Earth exactly? I hear it will be in five billion years, but that very rough.

It will be a hot day on Titan!

[Soul Surfer]

No.  The process for stars like the sun is not very violent or quick.  As the sun ages it slowly gets hotter and eventually will swell up to engulf the earth when it is a red giant in about 5 thousand million years time.

The big question is when this slow brightening will kill all life on earth?   This will probably be in another thousand million years or so.  This does not sound very long in the context that simple life has been around for several thousand million years but is much longer when you consider that the cambrian explosion of complex lifeforms only happened around 500 million years ago. so we probably have twice the evolution time since the trilobites to work out what to do about it!