The Fundamentals of Astronomy
Van Nostrand, 1927 - Astronomy - 307 pages
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actual angle appear astronomers atmosphere atoms average become bodies bright called caused celestial century CHAPTER close clusters color comet compared constellation course dark depends determined diameter direction discovered distance double earth east eclipse electrons energy equal equator fact fixed gases give greater heat Hence increased indicate intensity interesting known latitude length less light lines look magnitude March Mars mass mean measured meridian meteors method miles months moon moon's motion moving nearly nebula objects observations Observatory orbit parallax pass period photographic planet PLATE pole position possible present pressure probably radiation rays rise rotation seen separated side sidereal solar space spectroscope spectrum spiral stars sun-spot sun's surface telescope temperature tion Venus whole
Page 94 - Newton's law of gravitation states that any two bodies attract each other with a force proportional to the product of their masses and inversely proportional to the square of the distance between them, ie, (3.
Page 11 - Newton generalized the law of attraction into a statement that every particle of matter in the universe attracts every other particle with a force which varies directly as the product of their masses and inversely as the square of the distance between them; and he thence deduced the law of attraction for spherical shells of constant density.
Page 68 - This means the average time elapsing from new moon to new moon, or from full moon to full moon.
Page 9 - Harmonics ; what I had promised my friends in the title of this book, which I named before I was sure of my discovery ; what, sixteen years ago, I urged as a thing to be sought; that for which I joined Tycho Brahe, for which I settled in Prague, for which I have devoted the best part of my life to astronomical contemplations ; — at length I have brought to light, and have recognised its truth beyond my most sanguine expectations.
Page 10 - God far away from the confines of Egypt. If you forgive me, I rejoice; if you are angry, I can bear it: the die is cast, the book is written ; to be read either now or by posterity, I care not which : it may well wait a century for a reader, as God has waited six thousand years for an observer.
Page 13 - I know not what the world will think of my labors, but to myself it seems that I have been but as a child playing on the sea-shore ; now finding some pebble rather more polished, and now some shell rather more agreeably variegated than another, while the immense ocean of truth extended itself, unexplored, before me.
Page 90 - The square of the period of a planet is proportional to the cube of its mean distance from the Sun.
Page 22 - B, which is in the red near the end of the spectrum ; c is farther advanced in the red ; D is in the orange ; E, in the green ; F, in the blue ; G, in the indigo ; and H, in the violet.
Page 90 - ... attracts every other particle with a force proportional to the product of the masses and inversely proportional to the square of the distance between them.
Page 285 - Maanen, these circumstances produce the effect of winding up the arms. Basing his computations on Van Maanen's results, Jeans computes the mass and finds the density of the gas remaining in the nucleus of some of the very long-armed nebulae, nearly all of whose material has been ejected. It comes out smaller than the pressure in the best vacuum pumps. He says: "The small amount of gas in an ordinary electric light bulb, if spread out through St. Paul's Cathedral, would still be something like 10,000...