The Heavens: An Illustrated Handbook of Popular AstronomyR. Bentley, 1878 - 436 síður |
Common terms and phrases
Aldebaran appearance Arago astronomers atmosphere axis Boötes brightness brilliant celestial bodies celestial vault centre clouds clusters colour comets constellation craters dark density described diameter dimensions disappear disk double stars Earth elongated equator extreme fact globe heat heavens hemisphere Herschel horizon hypothesis immense intensity Jupiter Lastly length less light luminous luminous points lunar Mädler Mars mass mean distance measure Mercury meteors miles Milky Moon Moon's movement of rotation naked eye nearly nebula night nucleus observed orbit pass penumbra period phenomena photosphere physical constitution planet planetary pole portion position present proper motion rays regions remarkable revolution ring round the Sun satellites Saturn seen sidereal sidereal day solar days Solar System sometimes southern space spectrum sphere spots starry vault stars visible Sun's surface telescope terrestrial tion total eclipse traverse umbra Uranus variable variable stars varies velocity Venus whilst Zodiacal Light zone
Vinsælir kaflar
Síða 229 - We see it as Columbus saw America from the shores of Spain. Its movements have been felt, trembling along the far-reaching line of our analysis, with a certainty hardly inferior to that of ocular demonstration.
Síða 178 - ... of a greater degree of obliquity in the inclination of the axis of the planet to the plane of its orbit than what we find in several others. The same causes which made the inclination of the axis of Venus towards her orbit 75 degrees, may have turned that of Uranus a little further along, and so reversed the position of his poles.
Síða 139 - ... not coincident, and whose external curvature is towards the north. Beyond the second ridge a talus slopes gradually down northwards to the general level of the lunar surface, the whole presenting an appearance reminding the observer of the concentric moraines of the Rhone glacier. These ridges are visible for the whole period during which that portion of the Moon's surface is illuminated ; but it is only about the third day after the first quarter, and at the corresponding phase of the waning...
Síða 34 - The interior edge of the penumbra frequently appears extremely jagged; the bright ridges on its surface, which are directed nearly towards the centre of the spot, being seen projected to irregular distances on to the cloudy stratum [or umbra'], and looking much like a piece of coarse thatching with straw, the edge of which has been left untrimmed.
Síða 415 - Observations should always be commenced with the lowest power, gradually increasing it until the limit of the aperture, or of the atmospheric condition at the time, is reached : the former being taken as equal to the number of hundredths of inches which- the diameter of the object-glass contains. Thus, a 3^ -inch object-glass, if really good, should bear a power of 375 on double stars where light' is no object; the planets, the Moon, &c., will be best observed with a much lower power.
Síða 168 - ... the most remote condition, of which we have positive evidence, was that of small, detached, melted globules, the formation of which cannot be explained in a satisfactory manner, except by supposing that their constituents were originally in the state of vapour, as they now exist in the atmosphere of the Sun ; and, on the temperature becoming lower, condensed into these
Síða 182 - if their orbits are figured under the form of material rings, these rings will be found so entangled, that it would be possible, by means of one among them taken at hazard, to lift up all the rest...
Síða 139 - ... of controversy. In conclusion, this hypothesis suggests the probability that the other bodies belonging to our solar system have either already passed through a similar epoch, or are destined still to encounter it. With the exception of the polar ice of Mars we have hitherto obtained no certain glimpse into the thermal or meteorological condition of the planets : neither is the physical state of their surfaces accessible to our best telescopes. It is otherwise however with the moon, whose distance...
Síða 393 - Instruction should proceed from the known to the unknown, from the simple to the complex, from concrete to abstract notions, from analysis to synthesis.
Síða 52 - These are the general grounds on which we suspect the sun to be the agent which causes magnetic disturbances ; but there is also some reason to believe that on one occasion our luminary was caught in the very act. On the 1st of September, 1859, two astronomers, Messrs. Carrington and Hodgson, were independently observing the sun's disc, which exhibited at that time a very...