Chapter VI: Beginnings and Endings (2)

Looked at in terms of space, the message of astronomy is at best one of melancholy grandeur and oppressive vastness. Looked at in terms of time, it becomes one of almost endless possibility and hope. As denizens of the universe we may be living near its end rather than its beginning; for it seems likely that most of the universe had melted into radiation before we appeared on the scene. But as inhabitants of the earth, we are living at the very beginning of time. We have come into being in the fresh glory of the dawn, and a day of almost unthinkable length stretches before us with unimaginable opportunities for accomplishment. Our descendants of far-off ages, looking down this long vista of time from the other end, will see our present age as the misty morning of the world’s history; our contemporaries of to-day will appear as dim heroic figures who fought their way through jungles of ignorance, error and superstition to discover truth, to learn how to harness the forces of nature, and to make a world worthy for mankind to live in. We are still too much engulfed in the greyness of the morning mists to be able to imagine, however vaguely, how this world of ours will appear to those who will come after us and see it in the full light of day. But by what light we have, we seem to discern that the main message of astronomy is one of hope to the race and of responsibility to the individual—of responsibility because we are drawing plans and laying foundations for a longer future than we can well imagine.

INDEX

α Aquilæ, _see_ Altair
α Canis Majoris, _see_ Sirius
α Canis Minoris, _see_ Procyon
α Centauri, distance, 33, 35
luminosity and weight, 48
system of, 40, 263, 279, 280
α Herculis, 259, 272
α Lyrae, 33
α Orionis, _see_ Betelgeux
α-particles, 112, 116, 117, 118
and Plate XIII (p. 113)
α-rays, 111
α Scorpii, _see_ Antares
Absolute temperature, 102
Absorption lines and spectrum, 51, 126
Actino-uranium, 154, 155
Adams, J. C., 18, 19
Adams, W. S., 62, 343
Age of earth, 14, 151 ff., 248
of stars, 155 ff.
of sun, 180, 184
of universe, 336
Aitken, R. G., 171, 188
Altair (α Aquilæ), 33, 278
Andromeda, Great Nebula _M_ 31 in, Plate IV (p. 30),
30, 70, 71, 72, 204, 206, 208, 215, 335
age, 335
distance, 71
rotation, 206
size, 30
weight, 71, 208, 215
Andromedid meteors, 251
Angstrom unit, defined, 256
Angular momentum, conservation of, 205, 217, 232
of solar system, 232
Annihilation of matter, 185, 191, 193, 298, 331
Antares (α Scorpii), 259, 272, 273, 278
internal constitution of, 273, 291
Aquarid meteors, 251
Aristarchus of Samos, 2, 13
Aristotle, 2, 5
Arrangement of solar system, 16, 240 ff.
Bode’s law, 19, 20
Copernican, 3, 5, 6, 27, 32
Ptolemaic, 2, 4, 6, 8, 31
Asteroids, 17, 226, 240, 247, 252, 348
Ceres, 17
distance of, 19, 20, 252
Eros, 34
origin of, 247, 252
Aston, F. W., 119, 154, 185
Atmosphere, of earth, 195, 343
of moon, 196
of planets, 196, 343, 344, 348
of sun, 195
Atomic nuclei, 108, 117
disintegration of, 111, 117
size and weight of, 109
structure of, 119, 139, 147
Atomic numbers and weights, 110, 287
in stellar matter, 306, 311
Atomic theory, 92, 103
Atoms, 103, 318
structure of, 106
synthesis of, 148, 149, 185
Availability of Energy, 326, 329

β Aurigae, 54, 58
β-particles, 112, 113, 116, 145 and Plate XIII (p. 113)
β-rays, 111, 145
B.D. 6° 1309, _see_ Plaskett’s star
Bacon, Roger, 1
Becquerel, H., 110
Bentley, R., 197
Berenice’s hair, 39
Bessel, F. W., 33
Betelgeux (α Orionis), 259, 272, 278
Bickerton, A. W., 235
Biela’s comet, 251
Binary systems, 39, 40, 52, 54
birth of, 217
eclipsing, 54, 58
loss of weight in, 188, 228
orbits of, 46, 47, 167
origins of, 169, 219, 297
relative weights of components in, 188
subdivision in, 228
weights of, 48, 55
Birth of binary systems, 217
of nebulae, 204
of planets, 232, 237
of satellites, 232, 241
of stars, 209
Blackett. P. M. S., 117, 118
Blue stars, 62
Bode’s law, 19, 20, 252
Bohr, Niels, 124, 128, 129, 131, 304, 305
Bowen, J. S., 143
Boys, C. V., 44
Brownian movements, 159, 163
Bruno, Giordano, 3, 4, 344
Buffon, G. L. L., 235
Bumstead, H. A., 113
Burton, E. F., 143

γ-rays, 111, 114, 122, 139, 144, 145
Cameron, G. H., 143
Campbell, W. W., 321
Candle-power of stars, 49, 55, 179, 188;
_see_ Luminosity
Capella, 278
Cassini, D., 23
Cavity-radiation, 123, 255
Cepheid variables, 55, 56, 57, 59, 60, 70, 209
mechanism of, 223
Ceres (asteroid), 17
Chamberlin, T. C., 235, 236
Chaos, primaeval, density of, 202
evolution from, 202, 204, 229, 230
Charlier, C. V. L., 67
Clusters, globular, 63, 64, 68, 213, 216
moving, 39, 173, 216, 217
Coal, combustion of, 175, 191
Coal sack, 30
Comets, 247, 251
origin of, 238
Condensation-chamber of C. T. R. Wilson, 113, 117
Condensations in a gas, 198, 200, 203, 209, 237
Configurations of rotating masses, 221
Conservation, of angular momentum, 205, 217, 232
of energy, 99, 189, 326, 328
of matter, 189
Constellations, 36, 39
Cooke, H. L., 143
Copernican astronomy, 3, 5, 6, 27, 32
Copernicus, 3
Creation, of matter, 336
of universe, 79, 337
Crookes, Sir W., 106
Cycles and epicycles (Ptolemaic), 2, 3, 4
Cyclic processes in nature, 325, 329, 331

δ Cephei, 56, 223
δ-rays, 113
Darwin, Sir George, 224
de Sitter, cosmology of, 79 ff., 84, 86, 174
Democritus, 93
Density, of matter in space, 77, 331, 332
of nebulae, 208
of stars, 265-8, 273, 282
Diameters of stars, 260, 263-8, 272, 277-80
Diffraction grating, 114
Dimensions, of earth, 34
of galactic system, 65
of solar system, 20, 34
of universe, 77, 83, 86, 87
Discontinuity, in physics, 124 ff.
of matter, 93
Displacements of spectral lines, (de Sitter), 81
(Doppler), 52
(Einstein), 78, 323
Distances, of globular clusters, 63
of nebulae, 71, 73
of stars, 33, 35, 36, 61, 62, 63
Doppler effect, 52
Dwarf and Giant stars, 276
Dwarfs, white, 280, 283, 284, 292, 317, 319, 320, 322, 323, 335

Earth, age of, 14, 151, 155, 173, 247
as a planet, 16, 19, 230, 237, 243
birth of, 237, 243
dimensions of, 34
future of, 225, 226, 250, 346, 352
-moon system, 34, 225, 226, 240, 243, 250
orbit of, 35, 36, 227, 346
Eccentricity of binary orbits, 171
of ellipse (defined), 46
Eclipsing binaries, 54, 55, 56, 58
Eddington, A. S., 67, 84, 179, 184, 187, 224, 287, 288, 295
Einstein, A., (Cosmology), 74, 77, 79, 84
(Gravitation), 45, 75, 79, 161
(Quantum theory), 124, 126, 127
(Relativity), 74 ff., 186, 261
Electricity, positive and negative, 107
attraction and repulsion, 107, 129
Electromagnetic energy, 120, 121
Electron, 107, 112, 119, 121
orbits in atom, 108, 128
Ellipse, defined, 46
as atomic orbit, 129
as gravitational orbit, 46, 47, 227
Ellis, C. D., 139
Emden, R., 286, 288
Energy, 98, 120, 189, 326 ff.
availability of, 326, 328
conservation of, 99, 189
source of stellar, 184
weight of, 120
Epicycles, 2, 3, 4
Equipartition of energy, in a gas, 156
stellar, 160, 164, 170, 172
Eros, 34
Ether, existence of, 338
Evaporation, 94
Evening stars, 17
Evolution, from primaeval chaos, 202, 205, 229, 230
stellar, 313 ff.
Expanding universe, 84, 86 ff.
Extra-galactic nebulae, 30, 70, 82
densities of, 208
distance of, 71, 82
evolution of, 204 ff. and Plates XVI to XXI in order
number of, 72
rotation of, 205, 206
size of, 31
velocities of, 82, 84, 86
weights of, 71, 215

Faraday, M., 122
Final end of universe, 329 ff.
Fireball, 248
Fission of stars, 169, 217, 219, 222, 229
Fizeau, H. L., 261
Fluorescence, 115, 327
Fraunhofer, J. von, 105
Free-path of molecules, 98
Frequency of radiation, 115, 126, 127
Full radiator, 123, 255, 261

Galactic latitude and longitude, 24, 25
Galactic nebulae, 29, Plates III (p. 29), VI (p. 37), VII (p. 44)
Galactic system of stars, 23, 25, 65 ff., 211
number of, 68, 69, 215
rotation of, 66 ff., 214
weight of, 69, 215
Galileo, 1, 3, 4, 5, 8, 16, 24
Galle, J. G., 19
Gaseous masses in rotation, 206, 221
Gaseous state, nature of, 95
equipartition of energy in, 156
Gaunt, J. A., 309
Geodesy, 34
Geology, 150, 152
Gerasimovič, B. P., 321
Giant and Dwarf stars (defined), 276
Giant stars, internal constitution, 273, 290, 291, 310, 319
Globular clusters, 63, 65, 213, 216 and Plate IX (p. 63)
origin of, 216
shape of, 213
Goldsbrough, G. R., 250
Graham, T., 158
Gravitation, law of, 41, 45, 78, 161
cause of, 76
Gravitational instability, 197, 210, 237, 245, 246
Great Bear (cluster), 173, 216, 217
(constellation), 32, 39
Great nebulae, _see_ Extra-galactic nebulae

H.D. 1337, _see_ Pearce’s star
Halley, E., 151
Halley’s comet, 247, 251
Halm, J., 163
Hayford, J. F., 34
Heat, nature of, 100
effect of, on electrical structures, 141, 144
transport of, in a star, 307
Heat-death, 329, 330
Helium atom, 110, 119, 185, 305
Helmholtz, H., 177, 285
Henderson, T., 33
Herschel, Sir John, 23, 24, 211
Herschel, Sir William, 18, 23, 24, 25, 26, 28, 65, 70, 211
Hertzsprung, E., 59, 223, 275
Hesperus, 17
Hess, V. F., 143
Highly penetrating radiation, 143, 144, 191, 298, 299
Hinks, A. R., 65
Holmes, A., 152
Hubble, E., 71, 73, 77, 83, 84, 202, 204, 206, 208, 210
Humason, M. L., 82
Huyghens, C., 23
Hydrogen atom, 110, 119, 130, 135, 146
annihilation of, 146, 147, 192
electron orbits in, 128, 130, 192
Hyperbola, 46

Instability, dynamical, 202
gravitational, 197, 210, 237, 245, 246
Interferometer, 261, 272
Interstellar matter, 29, 30, 63
Interstellar space, temperature of, 102
Inverse square law, (electric), 129
(gravitational), 44, 45, 47
(luminosity), 24, 33
Invisible radiation, 115, 258, 259
Irregular nebulae, 206
Irregular variables, 55, 58
Island universes, 28, 31, 68
Isotopes, 118

Jeffreys, H., 155, 225, 226, 239
Jupiter, 4, 16, 17, 19, 207
birth of, 240 ff., 243, 244
rotation of, 168, 225
satellites of, 4, 23, 196, 240, 241, 243, 250
size of, 17
temperature of, 21
weight of, 45

_K_-ring of electrons in atom, 134, 138, 289, 291,
292, 302, 304, 318
Kant, I., 176, 230, 231
Kapteyn, J. C., 27, 65, 212, 214
Kelvin, Lord, 177, 285
Kepler, J., 5, 33, 46
Klein, O., 146, 148
Kolhörster, W., 143
Kramers, H. A., 309, 310
Kruger 60, 48, 278, 279, 280, 317
system of, 267, 279, 280

_L_-ring of electrons in atom, 134, 138, 289, 292, 302
Lalande 21185, 36, 265
Lane’s law, 286
Laplace, P. S., 230, 233 ff.
nebular hypothesis of, 230, 231, 232 ff.
Lead, radio-active, 154
Leavitt, Miss, 57
Lemaître, G., 84, 86, 174
Lenard, P., 106
Leonid shooting-stars, 250
Leslie, Sir John, 158
Leucippus, 93
Leverrier, U. J. J., 18, 19
Life in solar system, 341
in universe, 340, 342, 345
on Earth, 12, 342, 345
on Mars, 343
on Venus, 344, 347
Light, nature and composition of, 37, 50, 114
speed of, 37, 115
wave-length of, 115, 138
Light-year, 37
Lindblad, B., 67, 69
Lippershey, 1
Liquid masses in rotation, 219 ff.
Liquid stars, 222, 296 ff., 300, 304, 310
Lives of stars, _see_ Stars
Lockyer, Sir N., 314
Long-period variables, 56, 58, 61, 271, 319
Lowell, P., 19
Lucifer, 17
Lucretius, 93
Luminosity of stars, 48, 49, 179, 269, 278, 279, 280

_M_-ring of electrons in atom, 134, 289, 292, 293, 302
McLennan, J. C., 143
Magellanic clouds, 57, 210 and Plate XXI (p. 214)
Main-sequence stars, 279, 291, 295
Major planets, 16, 17
atmospheres on, 197
Man’s life on earth: past, 12, 16
future, 345 ff.
Marius, 31
Mars, 18, 19, 35
atmosphere of, 196, 343
birth of, 240, 243, 244
life on, 343
orbit of, 20, 239
rotation of, 225
satellites of, 240, 243, 250
temperature of, 21
Matter, annihilation of, 185, 191, 192, 315
conservation of, 189
Maxwell, J. C., 122, 157
Mayer, R., 176
Mercury, 4, 5, 16, 17, 19, 22, 35
absence of satellites, 243
atmosphere of, 196, 348
birth of, 240, 243
life on, 348
orbit of, 20, 45, 239
rotation of, 22, 224
Meteor, 238, 247, 248
Meteorite, 248
Michelson, A. A., 261
Milky way, 3, 23, 26, 27, 28, 30
Millikan, R. A., 143, 148
Minor planets, 16
Molecule, 94
collisions of, 97, 98, 102
equipartition of energy, 156
size of, 95
speed of, 96, 195
Moon, 4, 43
atmosphere of, 196
birth of, 243
distance of, 34, 43
eclipse of, 34
future of, 225, 226, 251
rotation of, 225
Moore, J. H., 321
Morning star, 17
Moulton, F. R., 235, 236
Moving clusters, 40, 173, 216
shape of, 216, 217
Munich 15040, 36, 264

Nebulae, classification of, 28
Nebulae, distance and size of, 31, 71, 72
extra-galactic, 28, 30, 70, 73, 82, 204 ff.
motions of, 82
rotation of, 205
weights of, 71, 204, 208, 215
_M_ 31, _see_ Andromeda, Great Nebula in
_M_ 33, 71, 210 and Plate XX (p. 213)
N.G.C. 4594, 71, 72, 204, 208 and Plate XV (p. 204)
Nebulae, galactic, 29 and Plates III (p. 29),
VI (p. 37), VII (p. 44)
Nebulae, planetary, 29, 273, 321, 323 and Plate II (p. 28)
Nebulae, spiral, 30, 236
Nebular hypothesis of Laplace, 230, 231, 232 ff.
Neptune, 16, 17, 18, 19
birth of, 240, 243, 244
rotation of, 225
satellite of, 240, 243
New stars (novae), 61, 351
Newton, Sir Isaac, (cosmogony), 197, 203
(distances of stars), 33
(law of gravitation), 44, 45, 46, 161, 197
(light and optics), 50, 105
Nicholas of Cusa, 3
Nishina, Y., 146, 148
Novae, 61, 351
Nucleus, atomic, _see_ Atomic

ο Ceti, 58, 272, 280
ο₂ Eridani, 268, 278, 280
_Ο_-type stars, 51, 321, 323
Obscuring matter in galactic system, 24, 30
Oort, J. H., 67, 84, 214
Opacity of stellar matter, 309
Orbit, of binary systems, 47, 167 ff., 224 ff.
of earth, 34, 36, 227
of moon, 34, 43, 226, 250
of planets, 45, 46, 237, 239, 245
of stars, 211, 213, 216
Oresme, 2
Orion, constellation of, 32, 39, 173

Paneth, F., 247
Parallactic measures of stellar distances, 33, 61, 63
Parallactic motion, defined, 33
Parallax, spectroscopic, 62, 303
Pearce’s star (H.D. 1337), 49, 54, 317
Period-luminosity law (Cepheid variables), 59-61
Perrin, J., 159, 184
Perseid shooting-stars, 251
Phases of moon and inner planets, 4, 5
Philolaus, 2
Phosphoros, 17
Photo-electric action, 128
Photography in astronomy, 37
Piazzi, G., 17
Planck, M., 123, 124, 126, 255
“Planet X,” 19
Planetary motions, 36, 45, 46, 78
Planetary nebulae, 29, 273, 321, 323 and Plate II (p. 28)
Planetary orbits, 45, 46, 237, 245
Planetesimal Hypothesis, 235, 236
Planets, arrangement of, 16, 19, 240
birth of (Laplace), 231, 234
birth of (Tidal Theory), 237, 240, 244
in the universe, 341, 349
motions and orbits of, 36, 45, 46, 78, 237, 239, 245
Plaskett, J. S., 67, 214
Plaskett’s star (B.D. 6° 1309), 49, 55, 269, 270, 272
Pleiades, 32, 39, 40, 173, 216
Plummer, H. C., 223
Pluto, 16, 18, 19, 20, 239, 240, 241, 243
birth of, 240, 243
temperature of, 20
Poincaré, H., 66, 285, 338
Poincaré’s theorem, 285, 291
Pressure in a gas, 97
in a star, 306
of radiation, 120
of radiation in a star, 290, 306
Primaeval chaos, evolution from, 202, 205, 229, 230
Proctor, R. A., 235
Procyon, 48, 266, 278, 279, 280
Proton, 119, 121
Proxima Centauri, 36, 40, 264, 278
Ptolemy, 2, 3, 4, 5, 6, 8, 31
Pythagoras, 2, 3, 5, 13

Quantum, defined, 126
Quantum theory, 122 ff., 137 ff., 286, 330, 331
Quotations, Arnold, Matthew, 5
Bede, 7
Bruno, Giordano, 3
Cornford, Frances, 11
Cusa, Nicholas of, 3
Galileo, 5
Meredith, George, 283
Newton, Sir Isaac, 197
Sackville-West, Victoria, 7
Shakespeare, 193

Radiation, 114 ff., 137 ff., 254 ff., 307
distribution by wave-length, 253
highly penetrating, 143, 144, 191, 298, 299
mechanical effects of, 120, 137, 290, 306
of sun, 55, 175, 256
pressure of, 120;
in a star, 290, 306
visible and invisible, 258, 259
wave-length of, 122, 255, 258
weight of, 120, 122, 136
Radio-activity, 110 ff., 153, 298
Rainbow, 50, 51, 105
Rayleigh, Lord, 94
Redman, H. O., 277, 349
Relativity, theory of, 74 ff., 186, 261, 323, 337
Ring nebula in Lyra, 29, 274 and Plate II (p. 28)
Rings of electrons, in atom, 134, 138, 289, 291 ff., 302, 304, 305
Roche, E., 245, 249
Roche’s limit, 246, 250, 251, 252
Rosse, Lord, 30
Rotating masses, of gas, 206, 221
of liquid, 219, 221
Rotating nebulae, 205
Rotating systems of stars, 168, 213
Rotation, of astronomical bodies, 168, 216
of galaxy, 66 ff., 214
of nebulae, 205
of stars, 217
Royds, T., 112
Russell, H. N., 187, 229, 276, 293, 299, 314
Russell diagram, 276, 277, 278, 282, 283, 291,
295, 302, 303, 314, 338
Rutherford, Sir E., 107, 111, 112, 117, 143, 154

_S_ Doradus, 182, 269, 270
St John, C. E., 343, 344
Salinity of oceans, 151
Sampson, R. A., 17, 308
Satellites, atmospheres on, 196
birth of (Laplace), 231
birth of (Tidal Theory), 241, 243, 246
discovery of, 23
Saturn, 16, 17, 18, 19, 32, 45
birth of, 240, 242, 243
rings of, 226, 231, 246, 247, 250
rotation of, 225
satellites of, 23, 196, 240, 241 ff., 250
temperature of, 21
Schrödinger, E., 305
Schwarzschild, K., 308
Seares, F. H., 26, 163, 281, 282
Sedimentation, 151
Shapley, H., 26, 59, 63, 65, 213, 216, 223, 247
Shooting-stars, nature of, 176, 247
origin of, 238, 247
swarms of, 247, 248, 251
Sirius, 36, 48, 259, 278, 279, 280, 316
system of, 265
Sirius _B_, 48, 262, 280, 292
Soddy, F., 111
Solar spectrum, 51, 105, 125, 256
Solar system, arrangement of, Bode’s law, 19
arrangement of (Copernican), 3, 5, 6, 27, 32
arrangement of (Ptolemaic), 2, 4, 6, 8, 31
atmospheres in, 194 ff., 343, 344, 347
orbits in, 45, 46, 224 ff., 238
origin of, 230 ff.
Sound, 96, 198
Spectra, stellar, 50, 125, 130 and Plate VIII (p. 51).
_See also_ Displacements
Spectral types, 51
relation to stellar weights, 164
relation to surface-temperatures, 257
Spectroscope, 50
Spectroscopic binaries, 52
orbits of, 171, 172
origin of, 169, 222, 223
Spectroscopic parallaxes, 62, 303
Spectroscopic velocities, 50
Spectroscopy, 105
Spectrum, 50
of sun, 50, 105, 125, 256
Spherical nebulae, 207, 218, 219
Spiral nebulae, 30, 236
arms of, 236
Stability of stellar structures, 295, 296, 300 ff.
Stars, ages of, 84, 155, 167, 173, 174, 186
arrangement of, 24, 65
birth of, 209
density of, 263 ff., 273, 282, 292
diameters of, 260 ff., 277, 278, 321
distances of, 31, 35, 37
evolution of, 313 ff.
internal constitution of, 285 ff.
internal temperatures of, 286
liquid, 222, 296 ff., 298, 301, 310
luminosity of, 49, 179, 180, 269
motions of, 36, 50, 66 ff., 164, 212, 213
number of, 68, 69, 88
spectra of, 51, 125, 130 and Plate VIII (p. 51).
_See also_ Displacements
stability of, 295, 296, 300 ff.
surface-temperatures of, 254, 257, 263 ff., 270, 271
variable, 55 ff., 223
weights of, 46, 48, 49, 164, 179, 268, 280 ff.
Star-streaming, 212, 214
Statistical methods in astronomy, 212, 213
Stellar, _see_ Stars
Struve, Otto, 223
Struve, W., 33
Sun, age of, 181, 184
candle-power of, 55
distance from earth, 34, 227, 346
future of, 348, 350
internal constitution of, 286, 290
internal temperature of, 286, 288
loss of weight of, 178, 227, 346
past history of, 180
position in galactic system, 26, 66
radiation of, 55, 175, 189, 190
rotation of, 168, 205, 245
surface-temperature of, 256
Surface-temperatures of planets, 21 ff., 346, 347
Surface-temperatures of stars, 254, 257, 263 ff., 270, 271
of sun, 256

Taylor’s comet, 251
Telescope, 1
Galileo’s, 2, 13
Herschels’, 25
Lord Rosse’s, 30
100-inch, 2, 20, 68, 72, 73
200-inch, 2, 73
Temperature, scale of, 102
Temperature-radiation, 140, 255
Thermodynamics, 326 ff.
first and second laws of, 326, 328
Thomson, Sir J. J., 106
Tidal friction, 224 ff.
Tidal theory of solar system, 236 ff.
Tides in binary stars, 224, 226
Titan (satellite of Saturn), 23, 196
Transit of Venus, 34
Transport of energy in a star, 307

Ultra-violet radiation, 116, 143, 144
Universe, age of, 334, 336
apparent expansion of, 84, 86 ff.
beginning of, 77, 332 ff.
final end of, 329 ff.
size of, 77, 84, 87
structure of, 74 ff., 87
Uranium atom, 110
disintegration of, 116, 121, 153
Uranus, 16, 17, 18, 19, 20
birth of, 240, 243, 244
rotation of, 225
satellites of, 23, 240, 243, 244
temperature of, 21

_V_ Puppis, 278, 317
van Maanen, A., 273
van Maanen’s star, 268, 274, 278, 292
van Rhijn, P. J., 26
Variable stars, 55 ff., 222, 271, 319
Vega (α Lyrae), 33
Velocities of stars, 36, 68, 163 ff.
Venus, 4, 5, 16, 17, 19, 34
absence of satellites, 243
atmosphere on, 197, 344
birth of, 240, 243
life on, 344, 347
phases of, 4, 5
rotation of, 224
temperature of, 22, 347
transit of, 34
Virgo, nebula N.G.C. 4594 in, 71, 72, 204, 208
and Plate XV (p. 204)
Visual binaries, orbits of, 170, 171
origin of, 169, 284

Wave-length of radiation, 115, 122
Wave-mechanics, 136, 305
White dwarf stars, 280, 283, 288, 317, 318,
319, 320, 323, 348, 349
Wilson, C. T. R., 113, 117
Wireless transmission, 115
Wolf 359, 36, 264, 269, 270

X-rays, 116, 138, 144, 307, 311

Zero (absolute) of temperature, 102
Zodiacal light, 238
Zwicky, F., 87

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