Planetary engineering

Planetary engineering is a class of hypothetical engineering activities designed to alter the condition of entire planets. Perhaps the best-known type of planetary engineering is terraforming, by which a planet's surface conditions are altered to be more like those of Earth. Planetary engineering is largely the realm of science fiction at current time, although some types of climate change on Earth could be considered a form of "geoengineering."

Geoengineering is the deliberate modification of Earth's environment on a large scale, in a sense "terraforming" Earth itself. Currently a great deal of debate takes place over the notion that human civilization has already inadvertently modified Earth's climate through the industrial emission of greenhouse gases, and proposals have been made to counter any such effects through further deliberate geoengineering. For example, some have proposed to put large mirrors in orbit which would modify the insolation received by Earth - either increasing or decreasing it, as the need arises. Large-scale sequestration of carbon dioxide inside geological formations or ocean sediment, modification of Earth's albedo with reflective or absorbtive materials spread over portions of its surface, or the alteration of rainfall patterns through the creation of artificial seas are other examples which have been seriously considered.