The application of photography to exact astronomy has created the necessity for new forms of apparatus to measure the relative positions of stellar and planetary images on photographic plates, and the relative positions of lines in photographic spectra.
With this end in view he expounded to the Berlin academy in 1849 a mode of determining an elliptic orbit from three observations, and communicated to that body in 1851 a new method of calculating planetary perturbations by means of rectangular coordinates (republished in W.
South of this anticyclone, from about the latitude of the Cape, we find the region where, on account of the uninterrupted sea surface right round the globe, the planetary circulation is developed to the greatest extent known; the pressure gradient is steep, and the region is swept continuously by strong westerly winds - the " roaring forties."
The formidable undertaking of reducing the accumulated planetary observations made at Greenwich from 1750 to 1830 was already in progress under Airy's supervision when he became Astronomer Royal.
Amongst the most important of his works not already mentioned may be named the following: - Mathematical Tracts (1826) on the Lunar Theory, Figure of the Earth, Precession and Nutation, and Calculus of Variations, to which, in the second edition of 1828, were added tracts on the Planetary Theory and the Undulatory Theory of Light; Experiments on Iron-built Ships, instituted for the purpose of discovering a correction for the deviation of the Compass produced by the Iron of the Ships (1839); On the Theoretical Explanation of an apparent new Polarity in Light (1840); Tides and Waves (1842).
His determination 2 of maximum and minimum values for the slowly varying planetary eccentricities was the earliest attempt to deal with the problem.
The discordance of their results incited Laplace to a searching examination of the whole subject of planetary perturbations, and his maiden effort was rewarded with a discovery which constituted, when developed and completely demonstrated by his own further labours and those of his illustrious rival Lagrange, the most important advance made in physical astronomy since the time of Newton.
Vii., 1776), Laplace announced his celebrated conclusion of the invariability of planetary mean motions, carrying the proof as far as the cubes of the eccentricities and inclinations.
It was followed by a series of profound investigations, in which Lagrange and Laplace alternately surpassed and supplemented each other in assigning limits of variation to the several elements of the planetary orbits.
That it formed the starting-point, and largely prescribed the course of thought on the subject of planetary origin is due to the simplicity of its assumptions, and the clearness of the mechanical principles involved, rather than to any cogent evidence of its truth.
It may be added that he first examined the conditions of stability of the system formed by Saturn's rings, pointed out the necessity for their rotation, and fixed for it a period (Io h 33 m) virtually identical with that established by the observations of Herschel; that he detected the existence in the solar system of an invariable plane such that the sum of the products of the planetary masses by the projections upon it of the areas described by their radii vectores in a given time is a maximum; and made notable advances in the theory of astronomical refraction (Mec. cel.
Though these objects only become visible in the atmosphere they are extra-terrestrial planetary bodies, and properly belong to the domain of astronomy.
The attention devoted to the matter soon elucidated the phenomena of meteors, and proved them to be small planetary bodies, practically infinite in numbers and illimitable in the extent and variety of their orbits.
The planetary theory and other particular dynamical problems likewise occupied his attention from time to time.
88), although now discarded, received countenance from the finding of Juno by Harding, and of Vesta by himself, in the precise regions of Cetus and Virgo where the nodes of such supposed planetary fragments should be situated.
97 Ursae majoris is of the planetary type; the earl of Rosse observed two spiral condensations turning in opposite directions, - hence its name, - the " Owl nebula."
The isothermal lines, in fact, suggest that in the vast area of the Pacific something corresponding to the " planetary circulation " is established, further investigation of which may be of extreme value in relation to current inquiries concerning the upper air.
2 There can scarcely be any doubt as to the origin of these seven (five) powers; they are the seven planetary divinities, the sun, moon and five planets.
This collective grouping of the seven (five) planetary divinities is derived from the late Babylonian religion, which can definitely be indicated as the home of these ideas (Zimmern, Keilinschriften in dem alien Testament, ii.
Period the Babylonian religion centred in the adoration of the seven planetary deities.
For in the Babylonian religion the planetary constellations are reckoned as the supreme deities.
We must also reject the theory that this degradation of the planetary deities into daemons is due to the influence of Hebrew monotheism, for almost all the Gnostic sects take up a definitely hostile attitude towards the Jewish religion, and almost always the highest divinity among the Seven is actually the creator-God of the, Old Testament.
But the form in which the whole is set forth is Oriental, and it must be carefully noted that the Mithras mysteries, so closely connected with the Persian religion, are acquainted with this doctrine of the ascent of the soul through the planetary spheres (Origen, Contra Celsum, vi.
He, moreover, sought in the events of his own life a verification of the theory of planetary influences; and it is to this practice that we owe the summary record of each year's occurrences which, continued almost to his death, affords for his biography a slight but sure foundation.
This extraordinary production is memorable as having announced the discovery of the "third law" - that of the sesquiplicate ratio between the planetary periods and distances.
His demonstration that the planes of all the planetary orbits pass through the centre of the sun, coupled with his clear recognition of the sun as the moving power of the system, entitles him to rank as the founder of physical astronomy.
But the fantastic relations imagined by him of planetary movements and distances to musical intervals and geometrical constructions seemed to himself discoveries no less admirable than the achievements which have secured his lasting fame.
He clearly perceived the significant analogy between terrestrial gravity and the force exerted in the solar system, and by the ingenious device of a circular pendulum illustrated the composite character of the planetary movements.
Next, dependent on the inclination of the earths axis, is the division of the planetary year into the terrestrial seasons, with winter and summer changes of temperature, wind-strength and precipitation: these seasonal changes are not of the restrained measure that is characteristic of the oceanic southern temperate zone, but of the exaggerated measure appropriate to the continental interruptions of ~the northern land-and-water zone, to which the term temperate is so generally inapplicable.
He quotes as an instance that Newton in this way added to the planetary appearances contained in Kepler's laws the gravitation of the planets to the sun, as a notion of causality not contained in the appearances, and thus discovered that gravitation is the cause of the appearances.
Kepler (1571-1630) was led by his study of the planetary motions to reject this method of statement as inadequate, and it is in fact incapable of giving a complete representation of the motions in question.
The warmed air of summer produces an area of low pressure in the west-central United States, which interrupts the belt of high pressure that planetary conditions alone would form around the earth about latitude 30; hence there is a tendency of the summer winds to blow inward from the northern Pacific over the Cordilleras toward the continental centre, and from the trades of the torrid Atlantic up the Mississippi Valley; conversely in winter time, the cold air over the lands produces a large area of high pressure from which the winds tend to flow outward; thus repelling the westerly winds of the northern Pacific and greatly intensifying the outflow southward to the Gulf of Mexico and eastward to the Atlantic. As a result of these seasonal alternations of temperature and pressure there is something of a monsoon tendency developed in the winds of the Mississippi Valley, southerly infiowing winds prevailing in summer and northerly outfiowing winds in winter; but the general tendency to inflow and outflow is greatly modified by the relief of the lands, to which we next turn.
Propitiatory abstinences were recommended when the natal asterism was menaced by unfavourable planetary conjunctions.
Thus in 1864 the spectroscope yielded him evidence that planetary and irregular nebulae consist of luminous gas - a conclusion tending to support the nebular hypothesis of the origin of stars and planets by condensation from glowing masses of fluid material.
He was several times a successful competitor for the prizes given by the Academy of Sciences of Paris; the subjects of his essays being: - the laws of motion (Discours sur les lois de la communication du mouvement, 1727), the elliptical orbits of the planets, and the inclinations of the planetary orbits (Essai d'une nouvelle physique celeste, 1735).
The first, for a memoir on the construction of a clepsydra for measuring time exactly at sea, he gained at the age of twenty-four; the second, for one on the physical cause of the inclination of the planetary orbits, he divided with his father; and the third, for a communication on the tides, he shared with Euler, Colin Maclaurin and another competitor.
The calculus of variations lay undeveloped in Euler's mode of treating isoperimetrical problems. The fruitful method, again, of the variation of elements was introduced by Euler, but adopted and perfected by Lagrange, who first recognized its supreme importance to the analytical investigation of the planetary movements.
Without astonishment," even to himself, regard being had to the great generality of the differential equations, he reached a result so wide as to include, as a particular case, the solution of the planetary problem recently obtained by him.
From this the distance of the sun can be at once determined by a fundamental equation of planetary motion.
By measurements giving the position of Mars among Planetary the neighbouring stars in the morning and evening, Parallaxes.
The planets in question appeared in the telescope as star-like objects which could be compared with the stars with much greater accuracy than a planetary disk like that of Mars, the apparent form of which was changed by its varying phase, due to the different directions of the sun's illumination.
In the appended treatise Sur la Cause de la pesanteur, he rejected gravitation as a universal quality of matter, although admitting the Newtonian theory of the planetary revolutions.