Index

The letter / preceding a page number indicates tabular material.

Absolute visual magnitude, 86 Acceleration, tolerance for high levels of, 11-13, t\2 Accretion hypothesis, 27 Accretion process, 60-61 ALLEN, c. w., 95, 106, 115 Allen's star tables, number of habitable planets in, 106, ¿108-109 Alpha Centauri absolute visual magnitude of, 86-87 orbit of, 111-112 probability of habitable planet in, 110-111 ASIMOV, ISAAC, 126 Atelectasis, 17 Atmospheres bodies without extensive, 30-31 classifications of, 39, 47 composition of, 16, 38-39 conditions for breathable, 13-20, il6, fl8, 54-56 CO2 concentrations in, 17 creation of oxygen in, 54 development of, 34-36 image distorting qualities of, 117-118 inert diluents in, 16-17 organic compounds in "primitive forms" of, 100 photosynthesis and development of, 63

removal of oxygen from, 55 replenishment of, 37

upper limits of diluents in, 16-17 variations within breathable, 14-15 See also Gases and Mass Atmospheric density, relationship of altitude to, 47, 57 Atmospheric entry, effects of planetary size on angle of, 47 Atmospheric pressure, relationship of altitude to, 57

Barometic pressure, breathable atmospheres and, 18-19 BEADLE, G. W., 100 BEMBOWER, W. C., 19 BERGER, R., 100

Beta Hydri, probability of habitable planet orbiting, 115 Binary star systems, 52, 76-80, 94-97, /96

ecospheres in, 95 illumination from, 76-80 median periods of, 95 planetary orbits within, 76 planets within widely separated, 125 probability of habitable planets within, 94-97 properties of, 76-80 spectroscopic doubles among, 95-96 visual doubles among, 95-96 Black spheres, temperatures of, 64-65

blanco, v. m., 42 bullard, e., 40 bussard, r. w., 2

calvin, m., 62, 100 Carbon dioxide, 17 Carbon, properties of, 63 Carotenoids, 100

chamberlain, j. w., 36 Chlorophyll, presence on other planets of, 99-100 cocconi, g., 113

"Critical escape level," effects of temperature on, 35-36 cullen, s. c., 16

Delta Pavonis, probability of habitable planet orbiting, 115 dole, s., 49

Earth atmosphere of, 55-56 atmospheric density gradient of, 47 critical escape layer of, 36 development of life on, 99-100 effect of changes in equatorial inclination on, 131 effect of impacting particles on rotation of, 61 effects of increased rotation on, 132 exosphere temperature of, 54 heating exosphere of, 36 hypothetical satellites of, 73-75 mass variation and life on, 130-131 oblateness of, 43-44 rate of precession in axis of, 67 retardation in rotation of, 70 rotation rate and tidal effects on, 46, 70

visual detection from space of, 120 Earthquakes, 22 Ecosphere, 71, 92 binary stars and single, 95

boundaries of, 71 definition of, 64

inclination of planet's equator and width of, 89 probability of planets orbiting within, 90-91, /92 visual doubles and, 95 eddington, a. s., 27

82 Eridani, probability of habitable planet orbiting, 115 Electrical activity, 22 Epsilon Eridani attempt to detect radio signals from, 113 probability of habitable planet orbiting, 113 Equatorial inclination habitability and range of, 65-66 planets with high, 125 relationship of distance from primary and, 63 See also Planets Escape velocity, 35-36, 53-54 Eta Cassiopeiae A, probability of habitable planet orbiting, 114 Exosphere, "critical escape layer" of, 36 temperatures of, 36-37

Free oxygen, habitability and, 98-99 fruton, j. s., 100

Galaxy age of, 98

"positional" effects on planets within, 126-127 total number of habitable planets in, 101-104 Gases behavior of atmospheric, 34 capture of, 35 escape of, 34-35, 61 toxic, 17-18 See also specific gases

Genetic variation, effect of "new"

planets on, 128-129 "Glare discomfort," 10. See Light Gravity dependency of atmosphere on, 57 effects on humans of high, 11-12,

127-128 See also Mass

Habitable planets. See Planets, habitable haldane, j. b. s., 62 Helium, in planetary atmospheres, 16, 36

henderson, l. j., 19, 62 hertzsprung, e., 23, 95 hoering, t. c., 99 hopkinson, r. g., 10 horowitz, n. h., 62 hoyle, f., 27

HR 7703 A, probability of habitable planet orbiting, 115 HR 8832, probability of habitable planet orbiting, 116 huang, s., 95 Hydrogen, 16, 36 "Hypothesis of desperation," 27

Illuminance, 64

habitability and maximum range of, 66 on earth's surface, 10 probability of habitability and conditions of, 88-90 See also Light Illumination contours, 77-78 ingalls, t. h., 15

jaffe, l. d., 2 jascheck, c., 95 jeans, sir james, 34, 41 jones, h. spencer, 3 jones, j. e., 34 joyce, james, 19 Jupiter atmosphere of, 5

unsuitability for human habitation of, 5

visual detection from space of, 119-120

Lambert body, 119 Lambert's law, 120 lamb, h., 41, 67 Life intelligent forms of, 100-101 probability that planets have developed, 99-100 See also Planets, habitable Light dependency of life forms on, 9-10 "glare discomfort," 10 human tolerance for, 10 limits of naked eye detection of, 10 photosynthesis and, 9-10 Lightning, nitrogen fixation by, 17 lowell, percival, 3

macdonald, g. a., 39 Maclaurin's spheroids, 41-46 Main-sequence stars absolute visual magnitude of, 83 age of, 68, 98, /98 characteristics of, 68, f84-8 5 estimated number of stars in each spectral class of, 83, ¿84-85 mass and spectral class of, 83, ¿84-85 star types among, 68 Mars, 2, 5

amount of oxygen in atmosphere of, 55 possibility of life on, 5 Mass, 53-58

atmospheric pressure as a function of, 55-57 contribution of planetary atmosphere to increase of, 36 habitability and minimum planetary, 54-56

relationship between habitability and, 53-56

rotational energy as a function of, 46 volcanism and, 40 See also Stars and Planets Matter, behavior under pressure of,

31-32 Mayo Clinic, 11 mc cuskey, s. w., 42 Mercury, 5

density of, 25, 30 retardation in rotation rate of, 70 unsuitability for human habitation, 5 metcalf, r. d., 10

Meteorites, dangers from infall of, 22 Meteorology, gaps in knowledge of,

25-26 Methane, 17 milankovitch, m., 64 miller, h., 11 miller, s. l., 100 Moon, unsuitability for human habitation of, 5 morrison, p., 113 Multiple star systems, 107 "Mutation-doubling" rate, 21-22

Neptune, 5

"interferences" between orbits of

Pluto and, 90 oblateness of, 42-44 poorly known properties of, 25 unsuitability for human habitation of, 5

newburn, r. l., jr., 30 Non-self-luminous bodies, definition of, 24

See also Planets and Satellites norton, e. f., 15

Oblateness, 41-45 definition of, 42 odell, n. e., 15 oparin, a. i., 62 Orbital eccentricity relationship between inclination and, 63

temperature and, 66-67

Orbital spacing, "forbidden regions"

and, 49 Orbits binary star systems and stable planetary, 76-77 See also Planets osretkar, a., 10 otis, a. b., 19 Oxygen toxicity, 14-15

Photodecomposition, 62-63 Photodissociation, 62-63 Photosynthesis, 8-10, 62-63, 99

See also Light Planetary systems, spacing of planets within, 90-91 Planetology, definition of, 24 Planets accretion process and formation of,

classification by atmospheres of,

39-41 composition of, 47-49 definition by mass of, 33 definition of, 24 detection of, 3, 117, 119 effect of growth on composition of, 47-49

effect of mass on composition of, 47 factors determining shape of, 31-32 factors influencing growth rate of,

28-29, 32 general physical properties of, 31-32 intrinsic properties of, 24 lack of adequate knowledge about, 25 life on other, 3

mass-density relationship of, 33-34 mass range of, 27-33 mean densities of, 29-30 origins of, 26-27 positional properties of, 24-25 resultant properties of, 25 rotation rate of, 58-61 special types of, 124-127 transition region between stars and, 27-29

Planets (continued) visual detection of, 117-121 volcanism in early life of, 61 Planets, habitable age as a requirement for, 80, 97-98 amount of water necessary for, 19 axial inclination and level of illuminance necessary for, 80 axial inclination extremes in, 65-66 binary star systems and, 76-80, tl9,

94-91 categories of, 4 characteristics of, 21, t2\ definition of, 4, 6 dust levels and, 20 effect of tides on, 70, 73 illuminance range for, 66 life forms on, 124 mass limits on primary stars for, 81 mass range of, 57-58, 80 orbital eccentricity limit for, 80 presence of nonhuman life necessary for, 20

probability of correct age, 97-98 probability of correct equatorial inclination, 88-90 probability of intelligent life on, 100 probability of life on, 98-101 probability of suitable mass, 91-93 probability of suitable orbital eccentricity levels, 93-94 probability that nearest stars possess, 106-116 probable existence of, 101-105, il02 probable number within 100 light-

years of earth, 105 range of surface gravity on, 58 range of tidal forces on, 73 rotation periods for, 80 summary of basic requisites for, 80-81 temperature requirements, 8-9 time from birth to habitability, 61-63 varieties of, 123-127 wind velocity on, 20 See also particular types, i.e.,

Satellite planets, Twin planets, etc.

Pluto, 5

"Population explosion," space flight and the, 134-135 Precession, 67 Primary stars braking effect on planets due to, 68-72 visual magnitudes of, 86-87 Project Ozma, 113 pugh, g., 15

Radiation, effect on life from differing, 129 Radioactivity, acceptable intensities of, 20-22 Radio waves, detection of, 121-122 Red giants, 68

numbers of, 86 Ringed planets, 125-126 Roche's limit, 73-75, 126 Roche's model, 41-46

relative geopotential at surface of, 45 roman, n. g., 119 Rotation effect on planets of, 58-61 effect on shape of planetary objects due to, 41

See also Oblateness effect on surface gravity due to, 45, 60 habitability and extremes in, 58-61 planetary objects and, 41-46 probability of suitable, 97 temperature and, 58-59 russell, h. n., 23

sanger, e., 2 Satellite planets, 124 Satellites rotation retardation due to, 72-74 tidal effects on planets due to, 72-75 Saturn,5

rings of, 125-126 Self-luminous bodies. See Stars 70 Ophiuchi A, probability of habitable planet orbiting, 114 shapley, harlow, 3, 27 sidgwick, n. v., 62-63 Sigma Draconis, probability of habitable planet orbiting, 115

slater, j. v., 12 Solarization, 10 Solar system atmospheres of planets in, 36-37 catastrophic theory of origin of, 87 "forbidden regions" within, 52 planetary rotation within, 42-46, t43 relationship of mass to rotation in planets of, 45-46 spacing of planets within, 49-52

?50, 90-91 tidal retardation effects in, 70, /71 "typicality of," 4 See also specific planets Space flight effect on human destiny of, 134-135 future feasibility of, 122-123 goals of, 3

"hibernation" techniques for, 123 spector, w. s., 7

Spectral absorption lines, detection of, code, c. f., 11

Spectral class. See Main-sequence stars Spectroscopic doubles. See Binary star systems spencer, d. f., 2

"Sphericity" of massive aggregates, 52

Stars classification of, 68 definition by mass of, 27 evolution of, 68 origins of, 27

possible habitable planets about the nearest, 110 probability of one habitable planet orbiting a given, 101-105 probability of paired habitable planets orbiting about, 102-103 probability of planets orbiting about, 87 rate of growth of, 28 transition region between planets and, 27-28 See also specific kinds of stars Stellar spectra, sequential arrangement of, 68

strughold, hubertus, 3, 64

Tau Ceti attempt to detect radio signals from, 113 probability of habitable planet orbiting, 114 tax, s., 62

Telescopes, use in space of, 118 Temperatures difficulty in predicting surface, 64 effect on planetary densities of high, 30 factors affecting seasonal, 66 habitability and, 8-9 human preferences in, 6-9 human tolerance for extremes in, 8 importance to critical escape level of, 35

relationship of food sources to, 7 relationship of light and, 10 tolerance of organisms to extremes in, 7-8

36 Ophiuchi A, probability of a habitable planet orbiting, 115 Three-body system, 76 Tidal effects, 69-71

braking, 70-75 Titius-Bode law of orbital distances, 49 tobias, c. a., 12 troitskaia, o. v., 8 Twin planets, 124 Two-sun planets, 124

University of California, 12 Uranus, 5

oblateness of, 42 poorly known properties of, 25 urey, h. c., 27, 34, 36, 44

van de kamp, p., 114 van den bos, w. h., 95 Velocity, problems of relativistic, 120-121 Venus, 2

difficulties for human habitation of, 5 effect of atmosphere on apparent density of, 29-30

Venus (continued]

retardation of rotation, 70 Visual doubles habitable planets and, 95 See also Binary star systems Volcanism, 41,61

development of planetary atmospheres through, 39-41 early life of planets and, 61 von weizsäcker, c. f., 27

Water appearance on planets of, 62 man's dependency on, 19-20 properties of, 19 weiss, f. j., 55 White dwarfs, 28, 68 wilson, c. l., 16 Wind velocity dust levels and, 20 See also Planets, habitable wulfeck, j. w., 10 wunder, c. c., 12, 128

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