Want to know what Earth will look like in the far future, after we've geo-engineered it to be a lot larger and the sun has gotten a lot colder? Here it is, thanks to NASA's amusing "extreme planet makeover" app.
Just visit the Extreme Planet Makeover site, and amuse yourself during your next coffee break by making Earth bigger and farther from the sun, or by changing our sun into a red dwarf star. Sliders let you determine your planet's size, age, and distance from the sun - while text windows tell you a little about the science behind your noodling. I recommend starting with the Earth preset, and then mutating the planet from there. Sadly, the Mars preset is pretty boring - I tried sending it back in time and putting it closer to the sun to see if it would become a water world, but no dice.