life-sustaining oxygen-nitrogen atmosphere
1Life — For other uses, see Life (disambiguation). Life (Biota / Vitae / Eobionti) …
2Extraterrestrial life — For fiction, see Extraterrestrials in fiction. For other uses, see Alien (disambiguation). A 1967 Soviet Union 16 kopeks postage stamp, depicting a satellite from an imagined extraterrestrial civilization …
3Terraforming — The terraforming (literally, Earth shaping ) of a planet, moon, or other body is the hypothetical process of deliberately modifying its atmosphere, temperature, surface topography or ecology to be similar to those of Earth to make it habitable by …
4climate — /kluy mit/, n. 1. the composite or generally prevailing weather conditions of a region, as temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds, throughout the year, averaged over a series of years. 2. a region or… …
5Hypothetical types of biochemistry — are forms of biochemistry speculated to be scientifically viable but not proven to exist at this time. While the kinds of living beings we know on earth commonly use carbon for basic structural and metabolic functions, water as a solvent and DNA… …
6Alternative biochemistry — is the speculative biochemistry of alien life forms that differ radically from those on Earth. It includes biochemistries that use elements other than carbon to construct primary cellular structures and/or use solvents besides water. Theories… …
7Earth — This article is about the planet. For other uses, see Earth (disambiguation). Earth   …
8Planetary habitability — is the measure of a planet s or a natural satellite s potential to develop and sustain life. As the existence of life beyond Earth is currently uncertain, planetary habitability is largely an extrapolation of conditions on Earth and the… …
9excretion — excretion1 /ik skree sheuhn/, n. 1. the act of excreting. 2. the substance excreted, as urine or sweat, or certain plant products. [1595 1605; < LL excretion (s. of excretio) that which is sifted out. See EXCRETE, ION] excretion2 /ik skree… …
10Methane — Methane …
