In 5 billion years the Sun will turn into a Red Giant

  It is said that in 5 billion years, the Sun will turn into a Red Giant. A Red Giant is a very large star of high luminosity and low surface temperature. Red giants are thought to be in a late stage of evolution when no hydrogen remains in the core to fuel nuclear fusion.

  When the Sun turns into a Red Giant, it will fuse the last of its hydrogen into helium, turn into a red giant and expand to 250 times its current size. At first, the Sun's loss of mass will loosen its gravitational pull on Earth, which will allow the planet to migrate to a wider orbit.

Some people think that the Earth might escape destruction - but survival now seems impossible, according to Peter Schröder of the University of Guanajuato in Mexico and Robert Smith of the University of Sussex in the UK. Earth's orbit will indeed widen, but Earth will also induce a "tidal bulge" on the Sun's surface, with its own gravitational pull. The bulge will lag just behind the Earth in its orbit, slowing it down enough to drag it to a fiery demise.

  There is still a little hope for humans. It is said that Earth's orbit could be tweaked by arranging the fly-by of a nearby asteroid to tug at it. This method could potentially maintain Earth's speed enough to keep it in a widening orbit, they say.

  However, people reading this post right now need not be too worried as this incident will only happen billions of years later, and we wont live to see it. Hopefully by then technology allows humans to do something to save the Earth.