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Planet

celestial body directly orbiting a star or stellar remnant
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A Planet (from Ancient Greek ἀστὴρ πλανήτης(astēr planētēs), meaning "wandering star") is an astronomical object orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals. The term planet is ancient, with ties to history, science, mythology, and religion. The planets were originally seen by many early cultures as divine, or as emissaries of deities. As scientific knowledge advanced, human perception of the planets changed, incorporating a number of disparate objects. In 2006, the International Astronomical Union (IAU) officially adopted a resolution defining planets within the Solar System. h

Earth, the white dwarf Sirius B, Venus; bottom row (reproduced and enlarged in lower image)—above: Mars and Mercury;below: the Moon, dwarf planets Pluto and Haumea
CONTENT : A - F , G - L , M - R , S - Z , See also , External links

Quotes

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Quotes are arranged alphabetically by author

A - F

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It is known that there is an infinite number of worlds, but that not every one is inhabited. Therefore, there must be a finite number of inhabited worlds. Any finite number divided by infinity is as near to nothing as makes no odds, so if every planet in the Universe has a population of zero... --Douglas Noel Adams.
 
I remember on the trip home on Appolo 11, it suddenly struck me that that tiny pea, pretty and blue, was the Earth... - Neil Armstrong.
 
...The earth's rotation makes the night and day,
The sun revolving through th'eccliptic way
Effects the various seasons of the year,...
 
Copernicus, who rightly did condemn
This oldest system, form'd a wiser scheme;
In which he leaves the Sun at Rest, and rolls
The orb terrestrial on its proper poles;
Which makes the night and day by this career,
And by its slow and crooked course the year.
The famous Dane, who oft the modern guides,
To earth and sun their Provinces divides:
The earth's rotation makes the night and day,
The sun revolving through th'eccliptic way
Effects the various seasons of the year,
Which in their turn for happy ends appear.
This scheme or that, which pleases best, embrace,...Richard Blackmore.
  • It is known that there is an infinite number of worlds, but that not every one is inhabited. Therefore, there must be a finite number of inhabited worlds. Any finite number divided by infinity is as near to nothing as makes no odds, so if every planet in the Universe has a population of zero then the entire population of the Universe must also be zero, and any people you may actually meet from time to time are merely the products of a deranged imagination.
 
Ceres (bottom left), the Moon and the Earth, shown to scale. - Gauss calculated the elements of the planet Ceres and his analysis proved him to be the first of theoretical astronomers no less than the greatest of 'arithmeticians.'
  • The fact that this chain of life existed [at volcanic vents on the seafloor] in the black cold of the deep sea and was utterly independent of sunlight—previously thought to be the font of all Earth's life—has startling ramifications. If life could flourish there, nurtured by a complex chemical process based on geothermal heat, then life could exist under similar conditions on planets far removed from the nurturing light of our parent star, the Sun.
  • There is nothing more mysterious than a TV set left on in an empty room. It is even stranger than a man talking to himself or a woman standing dreaming at her stove. It is as if another planet is communicating with you.
  • Copernicus, who rightly did condemn
    This oldest system, form'd a wiser scheme;
    In which he leaves the Sun at Rest, and rolls
    The orb terrestrial on its proper poles;
    Which makes the night and day by this career,
    And by its slow and crooked course the year.
    The famous Dane, who oft the modern guides,
    To earth and sun their Provinces divides:
    The earth's rotation makes the night and day,
    The sun revolving through th'eccliptic way
    Effects the various seasons of the year,
    Which in their turn for happy ends appear.
    This scheme or that, which pleases best, embrace,
    Still we the fountain of their motion trace.
    Kepler asserts these wonders may be done
    By the magnetic vertue of the sun,
    Which he, to gain his end, thinks fit to place
    Full in the center of that mighty space,
    Which does the spheres, where planets roll, include,
    And leaves him with attractive force endu'd.
    The sun, thus seated, by mechanic laws,
    The earth, and every distant planet draws;
    By which attraction all the planets found
    Within his reach, are turn'd in ether round.
 
...Kepler is said to have discovered the laws of planetary motion named after him, but no the many other 'laws' which he formulated. … Theories are especially precarious, as this century profoundly testifies.... -Richard J. Blackwell
  • Discovery always carries an honorific connotation. It is the stamp of approval on a finding of lasting value. Many laws and theories have come and gone in the history of science, but they are not spoken of as discoveries. Kepler is said to have discovered the laws of planetary motion named after him, but no the many other 'laws' which he formulated. … Theories are especially precarious, as this century profoundly testifies. World views can and do often change. Despite these difficulties, it is still true that to count as a discovery a finding must be of at least relatively permanent value, as shown by its inclusion in the generally accepted body of scientific knowledge.
 
There was yet another disadvantage attaching to the whole of Newton’s physical inquiries, … the want of an appropriate notation for expressing the conditions of a dynamical problem, and the general principles by which its solution must be obtained. By the labours of LaGrange, the motions of a disturbed planet are reduced with all their complication and variety to a purely mathematical question... - George Boole.
  • That the machine of Heaven is not a hard and impervious body full of various real spheres, as up to now has been believed by most people. It will be proved that it extends everywhere, most fluid and simple, and nowhere presents obstacles as was formerly held, the circuits of the Planets being wholly free and without the labour and whirling round of any real spheres at all, being divinely governed under a given law.
  • I would like to start by emphasizing the importance of surfaces. It is at a surface where many of our most interesting and useful phenomena occur. We live for example on the surface of a planet. It is at a surface where the catalysis of chemical reactions occur. It is essentially at a surface of a plant that sunlight is converted to a sugar. In electronics, most if not all active circuit elements involve non-equilibrium phenomena occurring at surfaces. Much of biology is concerned with reactions at a surface.
 
Gravitational microlensing.
  • Most known extrasolar planets (exoplanets) have been discovered using the radial velocity1, or transit methods. Both are biased towards planets that are relatively close to their parent stars, and studies find that around 17–30% of solar-like stars host a planet. Gravitational microlensing, on the other hand, probes planets that are further away from their stars. Recently, a population of planets that are unbound or very far from their stars was discovered by microlensing. These planets are at least as numerous as the stars in the Milky Way.
 
We only have to look around us to see how complexity … and psychic “temperature” are still rising: and rising no longer on the scale of the individual but now on that of the planet. This indication is so familiar to us that we cannot but recognize the objective, experiential, reality of a directionally controlled transformation of the Noosphere “as a whole. - Pierre Teilhard de Chardin.
  • We only have to look around us to see how complexity … and psychic “temperature” are still rising: and rising no longer on the scale of the individual but now on that of the planet. This indication is so familiar to us that we cannot but recognize the objective, experiential, reality of a directionally controlled transformation of the Noosphere “as a whole.”
 
Nicolaus Copernicus.
 
...axioms [seven] were granted me. They follow in this order.
There is no one center of all the celestial circles or spheres.
The center of the earth is not the center of the universe, but only of gravity and of the lunar sphere
All the spheres revolve about the sun as their mid-point, and therefore the sun is the center of the universe....- Nicolaus Copernicus.
  • After I had addressed myself to this very difficult and almost insoluble problem [circles of celestial sphere], the suggestion at length came to me how it could be solved with fewer and much simpler constructions than were formally used, if some assumptions (which are called axioms) [seven] were granted me. They follow in this order.
    There is no one center of all the celestial circles or spheres.
    The center of the earth is not the center of the universe, but only of gravity and of the lunar sphere.
    All the spheres revolve about the sun as their mid-point, and therefore the sun is the center of the universe.
    The ratio of the earth's distance from the sun to the height of the firmament is so much smaller than the ratio of the earth's radius to its distance from the sun that the distance from the earth to the sun is imperceptible in comparison with the height of the firmament.
    Whatever motion appears in the firmament arises not from any motion of the firmament, but from the earth's motion. The earth together with its circumjacent elements performs a complete rotation on its fixed poles in a daily motion, while the firmament and highest heaven abide unchanged.
    What appears to us as motions of the sun arise not from its motion but from the motion of the earth and our sphere, with which we revolve about the sun like any other planet. The earth has, then, more than one motion.
    The apparent retrograde and direct motion of the planets arises not from their motion but from the earth's. The motion of the earth alone, therefore, suffices to explain so many apparent inequalities in the heavens.
 
After a duration of a thousand years, the power of astrology broke down when, with Copernicus, Kepler, and Galileo, the progress of astronomy overthrew the false hypothesis upon which the entire structure rested, namely the geocentric system of the universe.... -Franz Cumo
 
A "planet" is defined a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit. - Definition by International Astronomical Union (IAU)
  • In 1684 Dr Halley came to visit him at Cambridge, after they had been some time together, the Dr asked him what he thought the Curve would be that would be described by the Planets supposing the force of attraction towards the Sun to be reciprocal to the square of their distance from it. Sir Isaac replied immediately that it would be an Ellipsis, the Doctor struck with joy & amazement asked him how he knew it, why saith he I have calculated it, whereupon Dr Halley asked him for his calculation without any farther delay. Sr Isaac looked among his papers but could not find it, but he promised him to renew it, & then to send it him.
 
The Solar System's four giant planets against the Sun - The word planet comes from the Greek for “wanderer,” because the planets' positions change relative to those of the stars. The eight (formerly nine) recognized planets that orbit the Sun are, in order of increasing distance, Mercury, Venus, Earth, Mars, Jupiter, Saturn,Uranus, and Neptune. The first four are called terrestrial planets and the next four giant, or Jovian, planets.
  • The word planet comes from the Greek for “wanderer,” because the planets' positions change relative to those of the stars. The eight (formerly nine) recognized planets that orbit the Sun are, in order of increasing distance, Mercury, Venus, Earth, Mars, Jupiter, Saturn,Uranus, and Neptune. The first four are called terrestrial planets and the next four giant, or Jovian, planets.
  • The terrestrial planets (of which Earth is the largest) are rocky with comparatively thin or negligible atmospheres. The Sun's heat is thought to have prevented the abundant volatile substances in the solar nebula from condensing in them as they formed. The giant planets formed farther out, where the gases were cool enough to condense, so the planets grew very massive and accumulated huge atmospheres of light gases, mainly hydrogen and helium. None of the giant planets has an accessible surface; their gaseous atmospheres gradually merge with their liquid interiors.
  • The planet : the planet Earth—used in informal phrases to say that someone is not aware of what is really happening or has ideas that are not realistic or practical.
 
Epitaph on tomb of Isaac Newton at Westminster Abbey.

G - L

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  • Sir, The Planet [Neptune] whose position you marked out actually exists. On the day on which your letter reached me, I found a star of the eighth magnitude, which was not recorded in the excellent map designed by Dr. Bremiker, containing the twenty-first hour of the collection published by the Royal Academy of Berlin. The observation of the succeeding day showed it to be the Planet of which we were in quest.
 
Phases of Venus -But what exceeds all wonders, I have discovered four new planets and observed their proper and particular motions, different among themselves and from the motions of all the other stars; and these new planets move about another very large star [Jupiter] like Venus and Mercury, and perchance the other known planets, move about the Sun.... - Galileo Galilei.
 
Animation of Mercury's and Earth's revolution around the Sun - I had rather be Mercury, the smallest among seven [planets], revolving round the sun, than the first among five [moons] revolving round Saturn. - Johann Wolfgang von Goethe.
 
...Therefore its former denominations, Pechblende, pitch-iron-ore, &c. are no longer applicable, and must be supplied by another more appropriate name. --- I have chosen that of Uranium, as a kind of memorial, that the chemical discovery of this new metal happened in the period of astronomical discovery of the new planet Uranus. - Martin Heinrich Klaproth.
 
Above the round domes of La Silla Observatory, three astronomical objects in the Solar System — Jupiter (top), Venus (lower left), and Mercury (lower right) ...First, That all Cœlestial Bodies whatsoever, have an attraction or gravitating power towards their own Centers, whereby they attract not only their own parts, and keep them from flying from them, as we may observe the Earth to do, but that they do also attract all the other Cœlestial bodies that are within the sphere of their activity; … -Robert Hook.
  • I shall explain a System of the World differing in many particulars from any yet known, answering in all things to the common Rules of Mechanical Motions: This depends upon three Suppositions. First, That all Cœlestial Bodies whatsoever, have an attraction or gravitating power towards their own Centers, whereby they attract not only their own parts, and keep them from flying from them, as we may observe the Earth to do, but that they do also attract all the other Cœlestial bodies that are within the sphere of their activity; and consequently that not only the Sun and Moon have an influence upon the body and motion the Earth, and the Earth upon them, but that Mercury also Venus, Mars, Saturn and Jupiter by their attractive powers, have a considerable influence upon its motion in the same manner the corresponding attractive power of the Earth hath a considerable influence upon every one of their motions also. The second supposition is this, That all bodies whatsoever that are put into a direct and simple motion, will continue to move forward in a straight line, till they are by some other effectual powers deflected and bent into a Motion, describing a Circle, Ellipse, or some other more compounded Curve Line. The third supposition is: That these attractive powers are so much the more powerful in operating, by how much the nearer the body wrought upon is to their own Centers. Now what these several degrees are I have not yet experimentally verified; but it is a notion, which if fully prosecuted as it ought to be, will mightily assist the Astronomer to reduce all the Cœlestial Motions to a certain rule, which I doubt will never be done true without it. He that understands the nature of the Circular Pendulum and Circular Motion, will easily understand the whole ground of this Principle, and will know where to find direction in Nature for the true stating thereof. This I only hint at present to such as have ability and opportunity of prosecuting this Inquiry, and are not wanting of Industry for observing and calculating, wishing heartily such may be found, having myself many other things in hand which I would first complete and therefore cannot so well attend it. But this I durst promise the Undertaker, that he will find all the Great Motions of the World to be influenced by this Principle, and that the true understanding thereof will be the true perfection of Astronomy.
  • We have the satisfaction to find, that in nature there is wisdom, system and consistency. For having, in the natural history of this earth, seen a succession of worlds, we may from this conclude that, there is a system in nature; in like manner as, from seeing revolutions of the planets, it is concluded, that there is a system by which they are intended to continue those revolutions. But if the succession of worlds is established in the system of nature, it is vain to look for anything higher in the origin of the earth. The result, therefore, of our present enquiry is, that we find no vestige of a beginning,-no prospect of an end.
 
Cosmic dust of the Andromeda Galaxy - Once I got into space, I was feeling very comfortable in the universe. I felt like I had a right to be anywhere in this universe, that I belonged here as much as any speck of stardust, any comet, any planet. - Mae C. Jemison.
  • I am sorry to say that there is too much point to the wisecrack that life is extinct on other planets because their scientists were more advanced than ours.
 
...it is absolutely certain and exact that the proportion between the periodic times of any two planets is precisely the sesquialterate proportion of their mean distances. - Johannes Kepler.
  • And if you want the exact moment in time, it was conceived mentally on 8th March in this year one thousand six hundred and eighteen, but submitted to calculation in an unlucky way, and therefore rejected as false, and finally returning on the 15th of May and adopting a new line of attack, stormed the darkness of my mind. So strong was the support from the combination of my labour of seventeen years on the observations of Brahe and the present study, which conspired together, that at first I believed I was dreaming, and assuming my conclusion among my basic premises. But it is absolutely certain and exact that the proportion between the periodic times of any two planets is precisely the sesquialterate proportion of their mean distances.
  • ...Pechblende does not belong either to the ores of zinc, or to those of iron, nor yet to the genus of tungsten or wolfram, and in general to none of the metallic substances hitherto known; but, on the contrary, that it consists of a peculiar, distinct, metallic substance. Therefore its former denominations, Pechblende, pitch-iron-ore, &c. are no longer applicable, and must be supplied by another more appropriate name. --- I have chosen that of Uranium, as a kind of memorial, that the chemical discovery of this new metal happened in the period of astronomical discovery of the new planet Uranus.
  • Knox was engaged in a theological discussion with scientist John Scott Haldane. 'In a universe containing millions of planets,' reasoned Haldane, 'is it not inevitable that life should appear on at least one of them?'
    'Sir,' replied Knox, 'if Scotland Yard found a body in your cabin trunk, would you tell them: 'There are millions of trunks in the world; surely one of them must contain a body? I think the would still want to know who put it there.'
  • The historian of science may be tempted to claim that when paradigms change, the world itself changes with them. Led by a new paradigm, scientists adopt new instruments and look in new places. even more important, during revolutions, scientists see new and different things when looking with familiar instruments in places they have looked before. It is rather as if the professional community had been suddenly transported to another planet where familiar objects are seen in a different light and are joined by unfamiliar ones as well.
 
NASA research facility in Ny-Ålesund.
  • Astronomy teaches the correct use of the sun and the planets. These may be put on a frame of little sticks and turned round. This causes the tides. Those at the ends of the sticks are enormously far away. From time to time a diligent searching of the sticks reveals new planets. The orbit of the planet is the distance the stick goes round in going round. Astronomy is intensely interesting; it should be done at night, in a high tower at Spitzbergen. This is to avoid the astronomy being interrupted. A really good astronomer can tell when a comet is coming too near him by the warning buzz of the revolving sticks.
  • After the planet becomes theirs, many millions of years will have to pass before a beetle particularly loved by God, at the end of its calculations will find written on a sheet of paper in letters of fire that energy is equal to the mass multiplied by the square of the velocity of light. The new kings of the world will live tranquilly for a long time, confining themselves to devouring each other and being parasites among each other on a cottage industry scale.
  • I would rather be ashes than dust!
    I would rather that my spark should burn out in a brilliant blaze than it should be stifled by dry-rot.
    I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet.
    The proper function of man is to live, not to exist.
    I shall not waste my days in trying to prolong them.
    I shall use my time.

M - R

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The Divine Comedy's Empyrean -Faustus: How many heavens or spheres are there?
Mephastophilis: Nine: the seven planets, the firmament, and the empyreal heaven.
Faustus: But is there not coelum igneum, et crystallinum? … - Christopher Marlowe.
  • Faustus: How many heavens or spheres are there?
    Mephastophilis: Nine: the seven planets, the firmament, and the empyreal heaven.
    Faustus: But is there not coelum igneum, et crystallinum?
    Meph.: No Faustus, they be but fables.
    Faustus: Resolve me then in this one question: Why are not conjunctions, oppositions, aspects, eclipses all at one time, but in some years we have more, in some less?
    Meph.: Per inaequalem motum respectu totius.
    Faustus: Well, I am answered. Now tell me who made the world.
    Meph.: I will not.
    Faustus: Sweet Mephastophilis, tell me.
    Meph.: Move me not, Faustus.
    Faustus: Villain, have I not bound thee to tell me any thing?
    Meph.: Ay, that is not against our kingdom.
    This is. Thou are damn'd, think thou of hell.
    Faustus: Think, Faustus, upon God that made the world!
    Meph.: Remember this.
    Faustus: Ay, go, accursed spirit, to ugly hell!‘Tis thou has damned distressed Faustus’s soul. Is’t not too late.
 
For nature is a perpetual circulatory worker, generating fluids out of solids, and solids out of fluids, fixed things out of volatile, & volatile out of fixed, subtle out of gross, & gross out of subtle, Some things to ascend & make the upper terrestrial juices, rivers and the atmosphere;... - Sir Isaac Newton.
  • For nature is a perpetual circulatory worker, generating fluids out of solids, and solids out of fluids, fixed things out of volatile, & volatile out of fixed, subtle out of gross, & gross out of subtle, Some things to ascend & make the upper terrestrial juices, rivers and the atmosphere; & by consequence others to descend for a requital to the former. And as the earth, so perhaps may the sun imbibe this spirit copiously to conserve his shining, & keep the Planets from receding further from him. And they that will, may also suppose, that this spirit affords or carries with it thither the solary fuel & material principle of light; And that the vast aethereal spaces between us, & the stars are for a sufficient repository for this food of the sun and planets.
  • Thus far I have explained the phenomena of the heavens and of our sea by the force of gravity, but I have not yet assigned a cause to gravity. Indeed, this force arises from some cause that penetrates as far as the centers of the sun and planets without any diminution of its power to act, and that acts not in proportion to the quantity of the surfaces of the particles on which it acts (as mechanical causes are wont to do) but in proportion to the quantity of solid matter, and whose action is extended everywhere to immense distances, always decreasing as the squares of the distances.
  • Seeing therefore the variety of Motion which we find in the World is always decreasing, there is a necessity of conserving and recruiting it by active Principles, such as are the cause of Gravity, by which Planets and Comets keep their Motions in their Orbs, and Bodies acquire great Motion in falling; and the cause of Fermentation, by which the Heart and Blood of Animals are kept in perpetual Motion and Heat; the inward Parts of the Earth are constantly warm'd, and in some places grow very hot; Bodies burn and shine, Mountains take fire, the Caverns of the Earth are blown up, and the Sun continues violently hot and lucid, and warms all things by his Light. For we meet with very little Motion in the World, besides what is owing to these active Principles. And it were not for these Principles the Bodies of the Earth, Planers, Comets, Sun, and all things in them would grow cold and freeze and become inactive masses; and all Putrefaction, Generation, Vegetation and Life would cease; and the Planets and Comets would not remain in their Orbs.
  • That the squares of the periodic times are proportion to the cubes of the major-axes. These laws were discovered by Kepler from observations made on Mars and stated by analogy as general laws, which, although not rigidly true, are sufficiently near to the truth to have led to the discovery of the law of attraction of the bodies of the solar system. The deviation from complete accuracy is due to the facts, that the planets are not of inappreciable mass, that, in consequence, they disturb each other's orbits about the Sun, and, by their action on the Sun itself, cause the periodic time of each to be shorter than if the Sun were a fixed body, in the subduplicate ratio of the mass of the Sun to the sum of the masses of the Sun and Planet; these errors are appreciable although very small, since the mass of the largest of the planets, Jupiter, is less than 1/1000th of the Sun's mass.
  • Klaatu: So long as you were limited to fighting among yourselves -- with your primitive tanks and planes -- we were unconcerned. But soon you will apply atomic energy to space ships -- and then you become a threat to the peace and security of other planets. That, of course, we cannot tolerate.
 
Penguins are an indicator of the health of our watery planet, and if they are unable to survive, we had better take notice or we might find our own survival threatened. - Roger Tory Peterson.
  • Penguins are an indicator of the health of our watery planet, and if they are unable to survive, we had better take notice or we might find our own survival threatened.
  • The nervous system is the most complex and delicate instrument on our planet, by means of which relations, connections are established between the numerous parts of the organism, as well as between the organism, as a highly complex system, and the innumerable, external influences. If the closing and opening of electric current is now regarded as an ordinary technical device, why should there be any objection to the idea that the same principle acts in this wonderful instrument? On this basis the constant connection between the external agent and the response of the organism, which it evokes, can be rightly called an unconditioned reflex, and the temporary connection—a conditioned reflex.
 
Plato.
 
...The heavenly bodies, or the spheres or whorls in which they lie, are arranged one within another in the following order:
1. The Fixed Stars.
2. Saturn.
3. Jupiter.
4. Mars.
5. Mercury.
6. Venus.
7. The Sun.
8. The Moon.
This order is as good as any other that can be framed under a geocentric hypothesis... - Plato.
  • The Spirits survey the heavens and the earth and all the harmonious motions of the universe. They see the heavenly bodies set in revolving whorls, which, whorl within whorl, combine to form the Spinning-whorl on the Spindle of Necessity; and the Goddess holds the spindle on her knee, and spins the thread which the Fates wind, unwind and cut. The heavenly bodies, or the spheres or whorls in which they lie, are arranged one within another in the following order:
    1. The Fixed Stars.
    2. Saturn.
    3. Jupiter.
    4. Mars.
    5. Mercury.
    6. Venus.
    7. The Sun.
    8. The Moon.
    This order is as good as any other that can be framed under a geocentric hypothesis
  • As the whorls differ from one another in respect of “ breadth of rim”, the first and outermost whorl is that which has its circular rim the broadest, and the sixth whorl comes next to it in regard to breadth of rim; and, proceeding in order of breadth, the fourth whorl comes third, and the eighth fourth, and the seventh fifth, and the fifth sixth, and the third seventh, and the second eighth.' Thus we have now a new classification of the heavenly bodies, in the following sequence:
    1. The Fixed Stars.
    2. Venus.
    3. Mars.
    4. The Moon.
    5. The Sun.
    6. Mercury.
    7. Jupiter.
    8. Saturn.
 
360-degree panorama view of the Milky Way Galaxy...The Milky Way would girdle the heavens as before; some of our familiar constellations, such as Orion, would be little changed, though others would be greatly altered by the shifting of the nearer stars. An unfamiliar brilliant star, between Cassiopeia and Perseus would be—the Sun. Looking back at it with our telescopes, we could photograph its spectrum, observe its motion among the stars, and convince ourselves that it was the same old Sun; but what had happened to the rest of our planetary system we would not know. - Henry Norris Russell.
  • The Sun is no lonelier than its neighbors; indeed, it is a very common-place star,—dwarfish, though not minute,—like hundreds, nay thousands, of others. By accident the brighter component of Alpha Centauri (which is double) is almost the Sun's twin in brightness, mass, and size. Could this Earth be transported to its vicinity by some supernatural power, and set revolving about it, at a little less than a hundred million miles' distance, the star would heat and light the world just as the Sun does, and life and civilization might go on with no radical change. The Milky Way would girdle the heavens as before; some of our familiar constellations, such as Orion, would be little changed, though others would be greatly altered by the shifting of the nearer stars. An unfamiliar brilliant star, between Cassiopeia and Perseus would be—the Sun. Looking back at it with our telescopes, we could photograph its spectrum, observe its motion among the stars, and convince ourselves that it was the same old Sun; but what had happened to the rest of our planetary system we would not know.

S - Z

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If we lived on a planet where nothing ever changed, there would be little to do. There would be nothing to figure out. There would be no impetus for science. And if we lived in an unpredictable world, where things changed in random or very complex ways, we would not be able to figure things out. But we live in an in-between universe, where things change, but according to patterns, rules, or as we call them, laws of nature... - Carl Sagan.
 
A celestial map from the 17th century. -Astronomy may be revolutionized more than any other field of science by observations from above the atmosphere. Study of the planets, the Sun, the stars, and the rarified matter in space should all be profoundly influenced by measurements from balloons, rockets, probes and satellites.... - Lyman Spitzer, Jr..
  • If we lived on a planet where nothing ever changed, there would be little to do. There would be nothing to figure out. There would be no impetus for science. And if we lived in an unpredictable world, where things changed in random or very complex ways, we would not be able to figure things out. But we live in an in-between universe, where things change, but according to patterns, rules, or as we call them, laws of nature. If I throw a stick up in the air, it always falls down. If the sun sets in the west, it always rises again the next morning in the east. And so it becomes possible to figure things out. We can do science, and with it we can improve our lives.
 
Who are we? We find that we live on an insignificant planet of a humdrum star lost between two spiral arms in the outskirts of a galaxy, tucked away in some forgotten corner of a universe in which there are far more galaxies than people. - Carl Sagan.
  • This is the excellent foppery of the world: that when we are sick in fortune—often the surfeits of our own behaviour—we make guilty of our disasters the sun, the moon, and stars, as if we were villains on necessity, fools by heavenly compulsion, knaves, thieves, and treachers by spherical predominance, drunkards, liars, and adulterers, by an enforced obedience of planetary influence, and all that we are evil in, by a divine thrusting on. An admirable evasion of whoremaster man, to lay his goatish disposition on the charge of a star! My father compounded with my mother under the Dragon's tail and my nativity was under Ursa Major, so that it follows that I am rough and lecherous. Fut! I should have been that I am had the maidenliest star in the firmament twinkled on my bastardizing.
  • If we imagine an observer to approach our planet from outer space, and, pushing aside the belts of red-brown clouds which obscure our atmosphere, to gaze for a whole day on the surface of the earth as it rotates beneath him, the feature, beyond all others most likely to arrest his attention would be the wedge-like outlines of the continents as they narrow away to the South.
  • I am entitled to say, if I like, that awareness exists in all the individual creatures on the planet—worms, sea urchins, gnats, whales, subhuman primates, superprimate humans, the lot. I can say this because we do not know what we are talking about: consciousness is so much a total mystery for our own species that we cannot begin to guess about its existence in others.
  • From the rocket we can see the huge sphere of the planet in one or another phase of the Moon. We can see how the sphere rotates, and how within a few hours it shows all its sides successively … and we shall observe various points on the surface of the Earth for several minutes and from different sides very closely. This picture is so majestic, attractive and infinitely varied that I wish with all my soul that you and I could see it.
 
This success permits us to hope that after thirty or forty years of observation on the new Planet [Neptune], we may employ it, in its turn, for the discovery of the one following it in its order of distances from the Sun. Thus, at least, we should unhappily soon fall among bodies invisible by reason of their immense distance, but whose orbits might yet be traced in a succession of ages, with the greatest exactness, by the theory of Secular Inequalities. -
  • This success permits us to hope that after thirty or forty years of observation on the new Planet [Neptune], we may employ it, in its turn, for the discovery of the one following it in its order of distances from the Sun. Thus, at least, we should unhappily soon fall among bodies invisible by reason of their immense distance, but whose orbits might yet be traced in a succession of ages, with the greatest exactness, by the theory of Secular Inequalities.
  • I tell my students, with a feeling of pride that I hope they will share, that the carbon, nitrogen, and oxygen that make up ninety-nine per cent of our living substance were cooked in the deep interiors of earlier generations of dying stars. Gathered up from the ends of the universe, over billions of years, eventually they came to form, in part, the substance of our sun, its planets, and ourselves. Three billion years ago, life arose upon the earth. It is the only life in the solar system.
  • Scientists themselves readily admit that they do not fully understand the consequences of our many-faceted assault upon the interwoven fabric of atmosphere, water, land and life in all its biological diversity. But things could also turn out to be worse than the current scientific best guess. In military affairs, policy has long been based on the dictum that we should be prepared for the worst case. Why should it be so different when the security is that of the planet and our long-term future?
 
Scientists still do not appear to understand sufficiently that all earth sciences must contribute evidence toward unveiling the state of our planet in earlier times, and that the truth of the matter can only be reached by combing all this evidence.... -Alfred Wegener.
  • Scientists still do not appear to understand sufficiently that all earth sciences must contribute evidence toward unveiling the state of our planet in earlier times, and that the truth of the matter can only be reached by combing all this evidence.... It is only by combing the information furnished by all the earth sciences that we can hope to determine 'truth' here, that is to say, to find the picture that sets out all the known facts in the best arrangement and that therefore has the highest degree of probability. Further, we have to be prepared always for the possibility that each new discovery, no matter what science furnishes it, may modify the conclusions we draw.
  • One of the grandest generalizations formulated by modern biological science is that of the continuity of life; the protoplasmic activity within each living body now on earth has continued without cessation from the remote beginnings of life on our planet, and from that period until the present no single organism has ever arisen save in the form of a bit of living protoplasm detached from a pre-existing portion; the eternal flame of life once kindled upon this earth has passed from organism to organism, and is still, going on existing and propagating, incarnated within the myriad animal and plant forms of everyday life.

Anonymous

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  • Dilbert: And we know mass creates gravity because more dense planets have more gravity.
    Dogbert: How do we know which planets are more dense?
    Dilbert: They have more gravity.
    Dogbert: That's circular reasoning.
    Dilbert: I prefer to think of it as having no loose ends.

See also

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