(no subject)
1. number of star companions
>if more than one: tidal interactions would disrupt planetary orbits
>if less than one: not enough heat produced for life
2. parent star birth date
>if more recent: star would not yet have reached stable burning phase
>if less recent: stellar system would not yet contain enough heavy elements
3. parent star age
>if older: luminosity of star would not be sufficiently stable
>if younger: luminosity of star would not be sufficiently stable
4. parent star distance from center of galaxy
>if greater: not enough heavy elements to make rocky planets
>if less: stellar density and radiation would be too great
5. parent star mass
>if greater: luminosity output from the star would not be sufficiently stable
>if less: range of distances appropriate for life would be too narrow; tidal forces would disrupt the rotational period for a planet of the right distance
6. parent star color
>if redder: insufficient photosynthetic response
>if bluer: insufficient photosynthetic response
7. surface gravity
>if stronger: planet's atmosphere would retain huge amounts of ammonia and methane
>if weaker: planet's atmosphere would lose too much water
8. distance from parent star
>if farther away: too cool for a stable water cycle
>if closer: too warm for a stable water cycle
9. thickness of crust
>if thicker: too much oxygen would be transferred from the atmosphere to the crust
>if thinner: volcanic and tectonic activity would be too great
10. rotation period
>if longer: diurnal temperature differences would be too great
>if shorter: atmospheric wind velocities would be too great
11. gravitational interaction with a moon
>if greater: tidal effects on the oceans, atmosphere, and rotational period would be too severe
>if less: earth's orbital obliquity would change too much causing climatic instabilities
12. magnetic field
>if stronger: electromagnetic storms would be too severe
>if weaker: no protection from solar wind particles
13. axial tilt
>if greater: surface temperature differences would be too great
>if less: surface temperature differences would be too great
14. albedo (ratio of reflected light to total amount falling on surface)
>if greater: runaway ice age would develop
>if less: runaway greenhouse effect would develop
15. oxygen to nitrogen ratio in atmosphere
>if larger: life functions would proceed too quickly
>if smaller: life functions would proceed too slowly
16. carbon dioxide and water vapor levels in atmosphere
>if greater: runaway greenhouse effect would develop
>if less: insufficient greenhouse effect
17. ozone level in atmosphere
>if greater: surface temperatures would become too low
>if less: surface temperatures would he too high; too much uv radiation at surface
18. atmospheric electric discharge rate
>if greater: too much fire destruction
>if less: too little nitrogen fixing in the soil
19. seismic activity
>if greater: destruction of too many life-forms
>if less: nutrients on ocean floors would not be uplifted
About a dozen other parameters, such as atmospheric chemical composition, currently are being researched for their sensitivity in the support of life. However, the nineteen listed in Table 1 in themselves lead safely to the conclusion that much fewer than a trillionth of a trillionth of a percent of all stars will have a planet capable of sustaining life. Considering that the universe contains only about a trillion galaxies, each averaging a hundred billion stars, we can see that not even one planet would be expected, by natural processes alone, to possess the necessary conditions to sustain life. No wonder Robert Rood and James Trefil and others have surmised that intelligent physical life exists only on the earth. It seems abundantly clear that the earth, too, in addition to the universe, has experienced divine design.
http://www.reasons.org/resources/apologetics/design.shtml
>if more than one: tidal interactions would disrupt planetary orbits
>if less than one: not enough heat produced for life
2. parent star birth date
>if more recent: star would not yet have reached stable burning phase
>if less recent: stellar system would not yet contain enough heavy elements
3. parent star age
>if older: luminosity of star would not be sufficiently stable
>if younger: luminosity of star would not be sufficiently stable
4. parent star distance from center of galaxy
>if greater: not enough heavy elements to make rocky planets
>if less: stellar density and radiation would be too great
5. parent star mass
>if greater: luminosity output from the star would not be sufficiently stable
>if less: range of distances appropriate for life would be too narrow; tidal forces would disrupt the rotational period for a planet of the right distance
6. parent star color
>if redder: insufficient photosynthetic response
>if bluer: insufficient photosynthetic response
7. surface gravity
>if stronger: planet's atmosphere would retain huge amounts of ammonia and methane
>if weaker: planet's atmosphere would lose too much water
8. distance from parent star
>if farther away: too cool for a stable water cycle
>if closer: too warm for a stable water cycle
9. thickness of crust
>if thicker: too much oxygen would be transferred from the atmosphere to the crust
>if thinner: volcanic and tectonic activity would be too great
10. rotation period
>if longer: diurnal temperature differences would be too great
>if shorter: atmospheric wind velocities would be too great
11. gravitational interaction with a moon
>if greater: tidal effects on the oceans, atmosphere, and rotational period would be too severe
>if less: earth's orbital obliquity would change too much causing climatic instabilities
12. magnetic field
>if stronger: electromagnetic storms would be too severe
>if weaker: no protection from solar wind particles
13. axial tilt
>if greater: surface temperature differences would be too great
>if less: surface temperature differences would be too great
14. albedo (ratio of reflected light to total amount falling on surface)
>if greater: runaway ice age would develop
>if less: runaway greenhouse effect would develop
15. oxygen to nitrogen ratio in atmosphere
>if larger: life functions would proceed too quickly
>if smaller: life functions would proceed too slowly
16. carbon dioxide and water vapor levels in atmosphere
>if greater: runaway greenhouse effect would develop
>if less: insufficient greenhouse effect
17. ozone level in atmosphere
>if greater: surface temperatures would become too low
>if less: surface temperatures would he too high; too much uv radiation at surface
18. atmospheric electric discharge rate
>if greater: too much fire destruction
>if less: too little nitrogen fixing in the soil
19. seismic activity
>if greater: destruction of too many life-forms
>if less: nutrients on ocean floors would not be uplifted
About a dozen other parameters, such as atmospheric chemical composition, currently are being researched for their sensitivity in the support of life. However, the nineteen listed in Table 1 in themselves lead safely to the conclusion that much fewer than a trillionth of a trillionth of a percent of all stars will have a planet capable of sustaining life. Considering that the universe contains only about a trillion galaxies, each averaging a hundred billion stars, we can see that not even one planet would be expected, by natural processes alone, to possess the necessary conditions to sustain life. No wonder Robert Rood and James Trefil and others have surmised that intelligent physical life exists only on the earth. It seems abundantly clear that the earth, too, in addition to the universe, has experienced divine design.
http://www.reasons.org/resources/apologetics/design.shtml