The Evolution of the Stars and the Formation of the Earth1915 - 80 pages |
Common terms and phrases
absorption lines angles asteroids astronomers average blue stars bright lines clusters collision components condensed continuous spectrum density diameter direction distance distributed double stars Earth and Moon eccentricities effect elements equatorial evolution evolutionary processes exist fact faint galaxy gaseous nebulæ gravitational helium stars hemisphere Herschel hydrogen lines inner satellite interior irregular nebulæ Jupiter Jupiter and Saturn Kant's known Laplace Laplace's Lick Observatory light loss of heat major planets materials matter meteoric Milky moving nebulium nebulosity Neptune novæ nuclei observed orbits origin outer strata particles pass periodic comets Photographed planetary nebulæ planetesimal planetesimal hypothesis principal proper motions radiation rapidly red stars region revolve Right Ascension ring rotation satellites solar system solid spectra spectroscope speeds spheroid spiral nebula stellar system Sun's surface strata telescopes temperature tidal tides tion Uranus Uranus and Neptune vapors velocities visible volume of space west to east Wolf-Rayet stars zodiacal light
Popular passages
Page 212 - Uranus, and its one moon, this planet requiring 165 years to travel around the Sun. Again, as to the material which composes the solar system: its distribution is most remarkable. Nearly all of it is in the Sun. If we add together the masses of the major planets, the hundreds of asteroids, the satellites, make liberal allowance for the comets, etc., and call the total 1, then the mass of the Sun on the same scale is 744; that is, of 745 parts of matter composing our Solar System, 744 parts are in...
Page 189 - It only wanted the knowledge of thermodynamics to lead to a thoroughly definite explanation of all that is known regarding the present actions and temperatures of the earth, and of the sun and other heavenly bodies.
Page 161 - Sun's atmosphere would in themselves produce bright-line spectra of the elements involved. If these gases and vapors could in effect be removed, without changing underlying conditions, the remaining condensed body of the Sun should have a continuous spectrum. The cooler overlying gases and vapors absorb those radiations from the deeper and hotter sources which the gases and vapors would themselves emit, and thus form the dark-line spectrum of the Sun. The stretches of spectrum between the dark lines...
Page 189 - ... nature of the zodiacal light are similar in several regards to present-day beliefs. Kant wrote : I seek to evolve the present state of the universe from the simplest condition of nature by means of mechanical laws alone. In 1869 Sir William Thomson, afterwards Lord Kelvin, commented that Kant's attempt to account for the constitution and mechanical origin of the universe on Newtonian principles...
Page 185 - That 24 novas should occur in the Milky Way, where the stars are most numerous, and where the resisting materials may preferably prevail, is not surprising; and it should be repeated that at least three of the five occurring outside of the Milky Way were located in nebulous surroundings. The actual collision of two stars would necessarily be too violent...
Page 210 - ... between the earth-balls. Traveling outward from the Sun we come, first, to the small planet Mercury, its diameter a little more than one third the Earth's diameter, which revolves once around the Sun in 88 days; secondly, to the planet Venus, just a shade smaller than the Earth, with period of revolution 225 days; and thirdly, to the Earth and its moon, which revolve around the Sun in one year. Fifty per cent, farther out than the Earth is Mars, its diameter a trifle more than one half the Earth's,...
Page 215 - Thousands of spiral nebulas are known to exist, but not a single one has been found within the Milky Way. Our stellar system is believed to occupy a limited volume of space, somewhat the shape of a very flat pocket watch, and we see the Milky Way as a bright band encircling the sky, because looking toward it we are looking out through the greatest depth of stars. There is reason to suspect that there is an immense amount of obstructing material in our system, that would be most effective in its long...
Page 212 - II to 8 years, the orbits varying greatly in size, eccentricity and position of orbit planes; then we come to the giant Jupiter, its diameter 11 times the Earth's diameter, and 9 moons, the system completing a revolution about the Sun in 12 years; still farther out is Saturn, its diameter 9 times the Earth's, with its wonderful ring system and 9 moons, all revolving around the Sun in...
Page 183 - The so-called new stars, otherwise known as temporary stars, afford interesting evidence on this point. These are stars which .suddenly flash out at points where previously no stars were known to exist ; or, in a few cases, where a faint existing star has in a few days become immensely brighter. Twenty-nine such stars have been observed in the past three centuries, nineFlG. 17. The Dark Holes, or "Coal Sacks...
Page 182 - ... all the heat generable had been dissipated. This would not occur until all material in the universe had been combined into one body, or into two bodies in mutual revolution. However, if there are those who say that the universe in action is eternal, through the operation of compensating principles as yet undiscovered, no man of science is at present equipped to prove the contrary.