The cause of the supposed proper motion of the fixed stars, and an explanation of the apparent acceleration of the moon's mean motion; with other problems in astronomy. A sequel to The glacial epoch |
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The Cause of the Supposed Proper Motion of the Fixed Stars and an ... Alfred Wilks Drayson Попередній перегляд недоступний - 1874 |
Загальні терміни та фрази
18 hours 366 rotations angle angular distance annual annum appear ascension and declination astronomers calculate catalogue cause centre of polar change in direction change in right changes in stars circle described circle round circle traced circumference colatitude cone conical motion conical movement consequently course traced curve decrease demonstrated difference diurnal rotation earth rotates earth's axis ecliptic equator equinoxes evidence exactly fact fixed stars follows Glacial Epoch heavens traced hitherto increase interval latitude longitude ment moon moon's move round north polar distance obliquity obtain occur orbit plane point of Aries polar circle polar motion polar movement Pole-star precession problem radius relative right ascension round the pole round the sun solar day sphere star's successive transits supposed theorists theory tion traced a circle true centre uniform measure Ursa Majoris variation various stars vary its distance whilst winter solstice zenith
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Сторінка 29 - He states that the pole of the ecliptic is the centre of the circle traced by the earth's axis, and never varies its distance of 23° 28
Сторінка v - The obliquity of the ecliptic, which equals the angular distance of the pole of the heavens from the pole of the ecliptic, is not sensibly affected by precession.
Сторінка 201 - Solar time is that used for all the purposes of ordinary life, and is measured by the daily motion of the sun. A Solar Day is the interval of time between two successive transits of the sun over the same meridian ; and the hour-angle of the sun is called Solar Time.
Сторінка 207 - ... at right angles, will revolve with a like motion, round that diameter of the sphere which is at right angles to the plane of the ecliptic, and which therefore terminates in its poles. But since the pole of the celestial equator is upon this circle at a distance from the pole of the ecliptic equal to the obliquity of the ecliptic, it follows that the pole of the equator will be carried round the pole of the ecliptic, in a lesser circle parallel to the plane of the ecliptic, with a retrograde motion...
Сторінка 286 - Astronomy," described the movement of the pole as describing a circle round the pole of the ecliptic as a centre and at a uniform distance from it of 23° 28'. though in another article he admitted a decrease of obliquity of 48...
Сторінка 28 - It is found, then, that in virtue of the uniform part of the motion of the pole, it describes a circle in the heavens around the pole of the ecliptic as a centre, keeping constantly at the same distance of 23° 28...
Сторінка 34 - At present it is only 1° 83' from the polar point, »nd by its northerly precession in declination will gradually approach to within 26' 80" of it. This proximity to the actual pole will occur in AD 2095, but will not recur for 12,860 years. The period of the revolution of the celestial equinoctial pole about the pole of the ecliptic, is nearly 26,000 years ; the north celestial pole, therefore, will be about 13,000 years ; hence, nearly 49
Сторінка 286 - ... if anyone had correlated the positions and produced the arcs beyond the ecliptic poles, they would have been found to meet at one point C, and thus the whole matter of the second rotation would have been revealed ! Drayson goes on to say " Routine, however, won the day, and the theory that the pole of the heavens always traced a circle round the pole of the ecliptic as a centre remained accepted as a fact. Then it was .supposed that by employing more observers and building additional observatories,...
Сторінка xix - ... are the mere blind followers of ' authorities in science ' as about one to ten thousand, we find ourselves in a considerable minority." On the other hand, the amount of reliance which he places upon the intelligence of other persons is very slight, as may be seen from the following quotations :— "To a person unacquainted with geometry there seems nothing unsound in stating that the centre of a circle can vary its distance from the circumference and yet still always remain the centre ; and this...
Сторінка 34 - Observation shews that this change of situation of the pole and equator is nearly regular. The pole of the celestial equator appears to move with a slow and nearly uniform motion, in a lesser circle, round the pole of the ecliptic ; while the intersections of the equator and ecliptic move backward on the ecliptic, with a motion nearly uniform. This motion is at the rate of about 1° in 72 years, or more accurately 50...