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{{ActiveDiscuss}} {{Original research|date=January 2008}} <br /><br /> {{Expand-section|date=March 2008}}

File:Habitable Moon 1.0.1.jpg
Hypothetical Moon: Habitable for Alien Life only, or Human Life as well?

Planetary human habitability refers specifically to the conditions/parameters needed to support human life on so-called habitable planets or on so-called habitable moons.
The planet Earth's temperature extreme records are:

  • The hottest temperature measured was 57.8°C (136°F) at El Azizia, Libya on 1922-09-13
  • -89.2 °C (-128.5 °F), recorded on 21 July 1983 in Vostok, a Russian Antarctic research station located at the center of the East Antarctic Ice Sheet.

Some scientists like to use the terms "Earth-Like" and "habitable" for the sake of popular acceptance or to improve a theory's apparent validity,[1] but as can be seen from these records, even the planet Earth itself can be inhospitable to human life. For example, each year multitudes of people die from dehydration due to extreme heat (see 1995 Chicago heat wave). Similarly, many people freeze to death every year in sub-zero winter temperatures.[2]

"Life as we know it"[edit]

{{ActiveDiscuss}} {{Expand-section|date=March 2008}} All life on Earth uses DNA, RNA, Ribosomes, proteins, etc. so that all life on Earth seems to decend from a common ancestor whose attributes define what scientist mean when they say "life as we know it."[3] But human life on this planet or in this universe is not comparable with simpler forms of life, such as bacteria, when it comes to survivability of harsh climates: [4]

Planetary Parameter list[edit]

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  • Habitable/Survivable gravity range
  • Habitable/Survivable hydrosphere size and precipitation.
  • Habitable/Survivable atmopshere constituents (IPP).
  • Insolation vs. Greenhouse gases
  • Eccentricity, affects of: Seasonality, Cryosphere size variability, Desert sizes.
  • Axial tilt, affects: mild or extreme seasonality, cryosphere size, desert sizes.

Stellar Factors[edit]

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In order to support human-like life, a planet or moon must orbit around a star that falls somewhere between Spectral types F and M, [7] and it must be located at a distance from its parent star that falls within the star's habitable zone. [8] The planet must be somewhat similar in characteristics to Earth, including an atmosphere with a pressure of at least 900 but less than 3000 millibars, [9] suitable surface gravity, suitable partial pressures of gases, adequate surface temperature, an adequate amount of oxygen, an axial tilt of between 10 and 30 degrees [10], and of course a suitable climate. [11] It may also be helpful for the planet in question to have at least one large moon, to minimize the variation in climate and axial tilt. [12]

Habitable moons[edit]

A Water Cloud Jovian

According to astronomers, there may also be habitable moons orbiting around Jupiter-like gas giants. [13] Unlike planets, a moon may not have to lie within the main star's habitable zone, because a moon may pick up heat due to (or in addition to) tidal forces from its parent planet, as with Jupiter's moons Io and Europa. The moon must, however, orbit far enough away from the planet's radiation belt or it may not develop life.[14] Some scientists believe that these kinds of moons may be the most likely candidates for extraterrestrial life.[15]


  1. ^ Feynman, Richard P. (1974). "Cargo Cult Science" (PDF). Engineering and Science. 37:7. Retrieved 2007-07-19.  Unknown parameter |month= ignored (help)
  2. ^ Olivier Deschenes & Enrico Moretti. "Extreme Weather Events, Mortality and Migration" (PDF). 
  3. ^ Zimmer, Carl (2007). "Aliens Among us". Discover magazine.  Unknown parameter |month= ignored (help)
  4. ^ "Other Extreme Earth Life". 
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See also[edit]

External links[edit]

Category:Planetary science Category:Space colonization Category:Humans Category:Human geography Category:Environment Category:Astrobiology Category:Planetary engineering