The hypothetical planetary engineering process of deliberately modifying a planet'
s atmosphere, temperature, surface topography, and ecology to make it habitable for Earth-like life. It is the ultimate long-term project, taking centuries or millennia, using methods like introducing greenhouse gases to warm a frozen
world, redirecting comets to deliver water, or seeding genetically engineered microbes to produce
oxygen. It's playing god on a planetary scale, with untold risks and moral implications about the
rights of any existing native life.
Example: The classic literary example of Terraforming is Kim
Stanley Robinson's
Mars trilogy, which details the centuries-long process of warming
Mars, creating a breathable atmosphere, and establishing a biosphere. It's the transformation of a dead rock into a living world, a second Genesis for humanity.