"Eventually, there will be one last perfect day on earth..."
- Carl Sagan
Around 5 billion years from today, the sun will begin to exhaust its hydrogen fuel, and it's own energy production will lose the ancient tug of war it plays with gravity. The sun will expand as it becomes a red giant star for a brief couple millenia, and it will engulf the earth whole.
It will slowly receed and collapse into itself, forming a white dwarf barely the size of this planet, and emitting almost no more light than one of the distant stars we see in the sky.
However, that will not be the last day on earth. Earth will continue on, devoid of any life whatsoever, until about 1080 years from now, when ultimate entropy will kick in, and the very fabric of matter itself will begin to fall apart. While "days" will continue to elapse, the matter that had comprised earth will be part of the huge universe sized atoms floating around at an excruciatingly slow speed. So, really, it won't be earth any more. But the atoms that used to be earth will continue to see days pass. Ad infinitum.
So anyway, who wants ice cream?
I knew I would get msgs from people nit-picking this writeup. Listen, I don't know how the earth is going to end any more than you do, so lighten up.