A group of astronomers believe that mankind will soon be able to move the earth around in space. This would be needed because the sun is expected to get hotter in the next few million years frying life here if nothing is done.
All we need to change earths orbit is a large asteroid to fly past every 5-6,000 years which would provide the "gravitational sling shot" to move earth. The technique is similar to what is used to move space probes through the solar system.
In about 3 billion years the earth will be too hot to support any life unless it is moved further away from the sun, however the movement may destabilize other planets such as Venus and Mercury.