Habitable Worlds circling non-Sol like stars

[The Rev]

Is it possible, say, for a world like Earth (or, at least enough like Earth that people could live there without space suits, etc.) to orbit a Red Giant star? What would such a world be like?

$$\phi$$

The Rev

 

[Chronos]

The short answer is yes. In fact, Mars may someday become habitable. See:
http://www.nasa.gov/lb/vision/universe/starsgalaxies/frozenworlds.html

 

[Andromeda321]

Interesting. Sort of in conjunction if anyone's interested, I once read an article where they tested to see just how stable the Earth's orbit needed to be in order to be habitable to life. One orbit they had tested the Earth going as far in as Venus and as far out as Mars, but the verdict was you could still find comfortable temperatures on Earth around Norway and such.

 

[SpaceTiger]

To first order, an isotropic expansion of a star (like the sun changing to a red giant) shouldn't alter the orbits of the planets. There's no reason it couldn't retain a rocky planet (assuming it was beyond the outer envelope of the expanded star) during that process. The possibility of life surviving under these circumstances is a bit trickier, though. The solar spectrum would be dramatically changed and there would be strong stellar winds ejecting material into the solar system. I personally doubt that such a situation would be hospitable to life.