Suitability criteria - Revision history

https://www.risetvp.com/index.php?action=history&feed=atom&title=Suitability_criteria Suitability criteria - Revision history 2026-11-10T07:57:11Z Revision history for this page on the wiki MediaWiki 1.40.1 https://www.risetvp.com/index.php?title=Suitability_criteria&diff=3258&oldid=prev reskin: Test 2019-11-19T17:19:22Z

<p>Test</p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 17:19, 19 November 2019</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l2">Line 2:</td> <td colspan="2" class="diff-lineno">Line 2:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Low-mass planets are poor candidates for life for two reasons. First, their lesser [[gravity]] makes [[Celestial body atmosphere|atmosphere]] retention difficult. Constituent [[molecule]]s are more likely to reach [[escape velocity]] and be lost to space when buffeted by [[solar wind]] or stirred by collision. Planets without a thick atmosphere lack the matter necessary for primal [[biochemistry]], have little insulation and poor [[heat transfer]] across their surfaces (for example, [[Mars]], with its thin atmosphere, is colder than the Earth would be if it were at a similar distance from the Sun), and provide less protection against [[meteoroid]]s and high-frequency [[radiation]]. Further, where an atmosphere is less dense than 0.006 Earth atmospheres, water cannot exist in liquid form as the required [[atmospheric pressure]], 4.56 [[Torr|mm Hg]] (608 Pa) (0.18 [[inch of mercury|inch Hg]]), does not occur. The temperature range at which water is liquid is smaller at low pressures generally.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Low-mass planets are poor candidates for life for two reasons. First, their lesser [[gravity]] makes [[Celestial body atmosphere|atmosphere]] retention difficult. Constituent [[molecule]]s are more likely to reach [[escape velocity]] and be lost to space when buffeted by [[solar wind]] or stirred by collision. Planets without a thick atmosphere lack the matter necessary for primal [[biochemistry]], have little insulation and poor [[heat transfer]] across their surfaces (for example, [[Mars]], with its thin atmosphere, is colder than the Earth would be if it were at a similar distance from the Sun), and provide less protection against [[meteoroid]]s and high-frequency [[radiation]]. Further, where an atmosphere is less dense than 0.006 Earth atmospheres, water cannot exist in liquid form as the required [[atmospheric pressure]], 4.56 [[Torr|mm Hg]] (608 Pa) (0.18 [[inch of mercury|inch Hg]]), does not occur. The temperature range at which water is liquid is smaller at low pressures generally.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Secondly, smaller planets have smaller [[diameter]]s and thus higher surface-to-volume ratios than their larger cousins. Such bodies tend to lose the energy left over from their formation quickly and end up [[geology|geologically]] dead, lacking the [[volcano]]es, [[earthquake]]s and [[plate tectonics|tectonic activity]] which supply the surface with life-sustaining material and the atmosphere with temperature moderators like [[carbon dioxide]]. Plate tectonics appear particularly crucial, at least on Earth: not only does the process recycle important chemicals and minerals, it also fosters [[bio-diversity]] through continent creation and increased environmental complexity and helps create the convective cells necessary to generate [[Earth's magnetic field]].<ref>[[#Ward|Ward]], pp. 191–220</ref></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Secondly, smaller planets have smaller [[diameter]]s and thus higher surface-to-volume ratios than their larger cousins. Such bodies tend to lose the energy left over from their formation quickly and end up [[geology|geologically]] dead, lacking the [[volcano]]es, [[earthquake]]s and [[plate tectonics|tectonic activity]] which supply the surface with life-sustaining material and the atmosphere with temperature moderators like [[carbon dioxide]]. Plate tectonics appear particularly crucial, at least on Earth: not only does the process recycle important chemicals and minerals, it also fosters [[bio-diversity]] through continent creation and increased environmental complexity and helps create the convective cells necessary to generate [[Earth's magnetic field]].<ref>[[#Ward|Ward]], pp. 191–220</ref> </div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>"Low mass" is partly a relative label: the Earth is low mass when compared to the Solar System's [[gas giant]]s, but it is the largest, by diameter and mass, and the densest of all terrestrial bodies.<ref group=lower-alpha>There is a "mass-gap" in the Solar System between Earth and the two smallest gas giants, [[Uranus]] and [[Neptune]], which are 13 and 17 Earth masses. This is probably just chance, as there is no geophysical barrier to the formation of intermediate bodies (see for instance [[OGLE-2005-BLG-390Lb]] and [[Super-Earth]]) and we should expect to find planets throughout the galaxy between two and twelve Earth masses. If the star system is otherwise favorable, such planets would be good candidates for life as they would be large enough to remain internally dynamic and to retain an atmosphere for billions of years but not so large as to accrete a gaseous shell which limits the possibility of life formation.</ref> It is large enough to retain an atmosphere through gravity alone and large enough that its molten core remains a heat engine, driving the diverse geology of the surface (the decay of [[radioactive]] elements within a planet's core is the other significant component of planetary heating). Mars, by contrast, is nearly (or perhaps totally) geologically dead and has lost much of its atmosphere.<ref>{{cite web |url=http://csmres.jmu.edu/geollab/Fichter/PlateTect/heathistory.html |title=The Heat History of the Earth |work=Geolab |publisher=[[James Madison University]] |accessdate=11 May 2007 }}</ref> Thus it would be fair to infer that the lower mass limit for habitability lies somewhere between that of Mars and that of Earth or Venus: 0.3 Earth masses has been offered as a rough dividing line for habitable planets.<ref>{{cite journal |last=Raymond |first=Sean N. |last2=Quinn |first2=Thomas |last3=Lunine |first3=Jonathan I. |date=January 2007 |title=High-resolution simulations of the final assembly of Earth-like planets 2: water delivery and planetary habitability |journal=Astrobiology |arxiv=astro-ph/0510285 |doi=10.1089/ast.2006.06-0126 |volume=7 |pages=66–84 |pmid=17407404 |bibcode=2007AsBio...7...66R |issue=1 |url=http://cds.cern.ch/record/895337 |type=Submitted manuscript }}</ref> However, a 2008 study by the Harvard-Smithsonian Center for Astrophysics suggests that the dividing line may be higher. Earth may in fact lie on the lower boundary of habitability: if it were any smaller, plate tectonics would be impossible. Venus, which has 85% of Earth's mass, shows no signs of tectonic activity. Conversely, "[[super-Earth]]s", terrestrial planets with higher masses than Earth, would have higher levels of plate tectonics and thus be firmly placed in the habitable range.<ref>{{cite web |title=Earth: A Borderline Planet for Life? |work=Harvard-Smithsonian Center for Astrophysics |date=2008 |url=http://www.cfa.harvard.edu/press/2008/pr200802.html |accessdate=4 June 2008 }}</ref></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>"Low mass" is partly a relative label: the Earth is low mass when compared to the Solar System's [[gas giant]]s, but it is the largest, by diameter and mass, and the densest of all terrestrial bodies.<ref group=lower-alpha>There is a "mass-gap" in the Solar System between Earth and the two smallest gas giants, [[Uranus]] and [[Neptune]], which are 13 and 17 Earth masses. This is probably just chance, as there is no geophysical barrier to the formation of intermediate bodies (see for instance [[OGLE-2005-BLG-390Lb]] and [[Super-Earth]]) and we should expect to find planets throughout the galaxy between two and twelve Earth masses. If the star system is otherwise favorable, such planets would be good candidates for life as they would be large enough to remain internally dynamic and to retain an atmosphere for billions of years but not so large as to accrete a gaseous shell which limits the possibility of life formation.</ref> It is large enough to retain an atmosphere through gravity alone and large enough that its molten core remains a heat engine, driving the diverse geology of the surface (the decay of [[radioactive]] elements within a planet's core is the other significant component of planetary heating). Mars, by contrast, is nearly (or perhaps totally) geologically dead and has lost much of its atmosphere.<ref>{{cite web |url=http://csmres.jmu.edu/geollab/Fichter/PlateTect/heathistory.html |title=The Heat History of the Earth |work=Geolab |publisher=[[James Madison University]] |accessdate=11 May 2007 }}</ref> Thus it would be fair to infer that the lower mass limit for habitability lies somewhere between that of Mars and that of Earth or Venus: 0.3 Earth masses has been offered as a rough dividing line for habitable planets.<ref>{{cite journal |last=Raymond |first=Sean N. |last2=Quinn |first2=Thomas |last3=Lunine |first3=Jonathan I. |date=January 2007 |title=High-resolution simulations of the final assembly of Earth-like planets 2: water delivery and planetary habitability |journal=Astrobiology |arxiv=astro-ph/0510285 |doi=10.1089/ast.2006.06-0126 |volume=7 |pages=66–84 |pmid=17407404 |bibcode=2007AsBio...7...66R |issue=1 |url=http://cds.cern.ch/record/895337 |type=Submitted manuscript }}</ref> However, a 2008 study by the Harvard-Smithsonian Center for Astrophysics suggests that the dividing line may be higher. Earth may in fact lie on the lower boundary of habitability: if it were any smaller, plate tectonics would be impossible. Venus, which has 85% of Earth's mass, shows no signs of tectonic activity. Conversely, "[[super-Earth]]s", terrestrial planets with higher masses than Earth, would have higher levels of plate tectonics and thus be firmly placed in the habitable range.<ref>{{cite web |title=Earth: A Borderline Planet for Life? |work=Harvard-Smithsonian Center for Astrophysics |date=2008 |url=http://www.cfa.harvard.edu/press/2008/pr200802.html |accessdate=4 June 2008 }}</ref></div></td></tr>  </table>

reskin https://www.risetvp.com/index.php?title=Suitability_criteria&diff=2822&oldid=prev reskin: /* Mass */ 2018-12-06T20:34:16Z

<p><span dir="auto"><span class="autocomment">Mass</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 20:34, 6 December 2018</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1">Line 1:</td> <td colspan="2" class="diff-lineno">Line 1:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=== Mass ===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=== Mass ===</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">[[File:Mars sunset PIA00920.jpg|thumb|[[Mars]], with its [[Rarefaction|rarefied]] atmosphere, is colder than the Earth would be if it were at a similar distance from the Sun.]]</del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Low-mass planets are poor candidates for life for two reasons. First, their lesser [[gravity]] makes [[Celestial body atmosphere|atmosphere]] retention difficult. Constituent [[molecule]]s are more likely to reach [[escape velocity]] and be lost to space when buffeted by [[solar wind]] or stirred by collision. Planets without a thick atmosphere lack the matter necessary for primal [[biochemistry]], have little insulation and poor [[heat transfer]] across their surfaces (for example, [[Mars]], with its thin atmosphere, is colder than the Earth would be if it were at a similar distance from the Sun), and provide less protection against [[meteoroid]]s and high-frequency [[radiation]]. Further, where an atmosphere is less dense than 0.006 Earth atmospheres, water cannot exist in liquid form as the required [[atmospheric pressure]], 4.56 [[Torr|mm Hg]] (608 Pa) (0.18 [[inch of mercury|inch Hg]]), does not occur. The temperature range at which water is liquid is smaller at low pressures generally.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Low-mass planets are poor candidates for life for two reasons. First, their lesser [[gravity]] makes [[Celestial body atmosphere|atmosphere]] retention difficult. Constituent [[molecule]]s are more likely to reach [[escape velocity]] and be lost to space when buffeted by [[solar wind]] or stirred by collision. Planets without a thick atmosphere lack the matter necessary for primal [[biochemistry]], have little insulation and poor [[heat transfer]] across their surfaces (for example, [[Mars]], with its thin atmosphere, is colder than the Earth would be if it were at a similar distance from the Sun), and provide less protection against [[meteoroid]]s and high-frequency [[radiation]]. Further, where an atmosphere is less dense than 0.006 Earth atmospheres, water cannot exist in liquid form as the required [[atmospheric pressure]], 4.56 [[Torr|mm Hg]] (608 Pa) (0.18 [[inch of mercury|inch Hg]]), does not occur. The temperature range at which water is liquid is smaller at low pressures generally.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>  </table>

reskin https://www.risetvp.com/index.php?title=Suitability_criteria&diff=2821&oldid=prev reskin: Created page with "=== Mass === [[Mars, with its rarefied atmosphere, is colder than the Earth would be if it were at a similar distance f..." 2018-12-06T20:33:23Z

<p>Created page with "=== Mass === <a href="/index.php?title=File:Mars_sunset_PIA00920.jpg&action=edit&redlink=1" class="new" title="File:Mars sunset PIA00920.jpg (page does not exist)">thumb|[[Mars</a>, with its <a href="/index.php?title=Rarefaction&action=edit&redlink=1" class="new" title="Rarefaction (page does not exist)">rarefied</a> atmosphere, is colder than the Earth would be if it were at a similar distance f..."</p> <a href="//www.risetvp.com/index.php?title=Suitability_criteria&diff=2821">Show changes</a>

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