No one knows, though people have tried to predict it. In fact, claims of the imminent end of the world have been occurring for centuries, though not all "scares" gain as much publicity as say, the "rapture" prediction of May, 2011.
20 trillion
it ends on December 21 2012 and it ends there because Spain conquered them before they had time to continue not because the world is going to end at the time it ends.
How does the hydrosphere change the earth over time
Half of the Earth at a time.
Eventually the sun will die and when it does, it will expand past Earth and obliterate it, but that will be a long time from now.
No, they live on opposite ends of the earth and never meet in nature.
We say 'much time' as in "We don't have much time before the test begins."
There is no start time. It could be at sunrise (my opinion) but it ends at 9 PM.
12 years
5 hours a day .
It is impossible to mine Earth's core.
Earth, but there's not much difference.