Mercury is the smallest and closest planet to the Sun of the eight planets in the Solar System, with an orbital period of about 88 Earth days. Seen from Earth, it appears to move around its orbit in about 116 days, which is much faster than any other planet. It has no known natural satellites.The planet is named after the Roman deity Mercury, the messenger to the god.
- Quotes are arranged alphabetically by author
A - F
- I wol yow telle, as was me taught also,
The foure spirites and the bodies sevene,
By ordre, as ofte I herde my lord hem nevene.
The firste spirit quiksilver called is,
The seconde orpyment, the thridde, ywis,
Sal armonyak, and the firthe brimstoon.
The bodys sevene eek, lo! hem heer anoon:
Sol gold is, and Luna silver we threpe,
Mars iren, Mercurie quyksilver we clepe,
Saturnus leed, and Jupiter is tyn,
And Venus coper, by my fader kyn!
- The universe is globe-shaped, either because that is the most perfect shape of all, needing no joint, an integral whole; or because that is the most capacious of shapes, which is most fitting because it is to contain and preserve all...The first and highest of all is the sphere of the fixed stars, which contains itself and all things, and is therefore motionless. It is the location of the universe, to which the motion and position of all the remaining stars is referred. For though some consider that it also changes in some respect, we shall assign another cause for its appearing to do so in our deduction of the Earth's motion. There follows Saturn, the first of the wandering stars, which completes its circuit in thirty years. After it comes Jupiter which moves in a twelve-year long revolution. Next is Mars, which goes round biennially. An annual revolution holds the fourth place, in which as we have said is contained the Earth along with the lunar sphere which is like an epicycle. In fifth place Venus returns every nine months. Lastly, Mercury holds the sixth place, making a circuit in the space of eighty days. In the middle of all is the seat of the Sun. For who in this most beautiful of temples would put this lamp in any other or better place than the one from which it can illuminate everything at the same time? Aptly indeed is he named by some the lantern of the universe, by others the mind, by others the ruler. Trismegistus called him the visible God, Sophocles' Electra, the watcher over all things. Thus indeed the Sun as if seated on a royal throne governs his household of Stars as they circle around him. Earth also is by no means cheated of the Moon's attendance, but as Aristotle says in his book On Animals the Moon has the closest affinity with the Earth. Meanwhile the Earth conceives from the Sun, and is made pregnant with annual offspring. We find, then, in this arrangement the marvellous symmetry of the universe, and a sure linking together in harmony of the motion and size of the spheres, such as could be perceived in no other way. For here one may understand, by attentive observation, why Jupiter appears to have a larger progression and retrogression than Saturn, and smaller than Mars, and again why Venus has larger ones than Mercury; why such a doubling back appears more frequently in Saturn than in Jupiter, and still more rarely in Mars and Venus than in Mercury; and furthermore why Saturn, Jupiter and Mars are nearer to the Earth when in opposition than in the region of their occultation by the Sun and re-appearance. Indeed Mars in particular at the time when it is visible throughout the night seems to equal Jupiter in size, though marked out by its reddish colour; yet it is scarcely distinguishable among stars of the second magnitude, though recognized by those who track it with careful attention.
- We find then in this arrangement an admirable harmony of the world, and a dependable, harmonious interconnexion of the motion and the size of the paths, such as otherwise cannot be discovered. For here the penetrating observer can note why the forward and the retrograde movement of Jupiter appears greater than that of Saturn, and smaller than that of Mars, and again greater with Venus than with Mercury; and why such retrogression appears oftener with Saturn than with Jupiter, less often with Mars and Venus than with Mercury. Moreover, why Saturn, Jupiter, and Mars, when they rise in the evening, appear greater than when they disappear and reappear [with the sun]...And all this results from the same cause, namely the motion of the earth.
- Nicolaus Copernicus quoted in: Edwin Arthur Burtt The Metaphysical Foundations of Modern Physical Science: A Historical and Critical Essay, Routledge, Jun 23, 2014, p. 45
- The Solar System consists of eight "planets" Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A new distinct class of objects called "dwarf planets" exist. "Planets" and "dwarf planets" are two distinct classes of objects. The first members of the "dwarf planet" category are Ceres, Pluto and 2003 UB313 (temporary name).
- 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.
- My Seal-Ring
Mercury has cast aside
The signs of intellectual pride,
Freely offers thee the soul:
Art thou noble to receive?
Canst thou give or take the whole,
Nobly promise and believe?
Then thou wholly human art,
A spotless, radiant, ruby heart,
And the golden chain of love
Has bound thee to the realm above
G - L
- 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. As soon as this tract, which I shall send to all the philosophers and mathematicians as an announcement, is finished, I shall send a copy to the Most Serene Grand Duke, together with an excellent spyglass, so that he can verify all these truths.
- I therefore concluded, and decided unhesitatingly, that there are three stars in the heavens moving about Jupiter, as Venus and Mercury about the Sun; which at length was established as clear as daylight by numerous other observations. These observations also established that there are not only three, but four, erratic sidereal bodies performing their revolutions round Jupiter.
- Galileo Galilei in: Kate Aughterson The English Renaissance: An Anthology of Sources and Document, Routledge, Jun 1, 2002, p. 383
- 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 in: Rev. James Wood Dictionary of Quotations from Ancient and Modern, English and Foreign Sources:, Warne, 1893, p. 166
- The Pythagorean harmony of the spheres lives on to this day. In his Natural History (circa AD77), the Roman scientist and noble man Pliny the Elder considered formed by the earth and Moon to be a tone; Moon to Mercury a semi-tone; Mercury to Venus, a semi-tone; Venus to the Sun, a minor third; Sun to Mars, a tone, Mars to Jupiter, a semi-tone; Jupiter to Saturn, a semi-tone; and Saturn to the fixed stars, a minor third. The 'Pythagorean Scale' created from this musical arrangement is still recognised. And Pliny's report reveals not only a heavenly musical scale, but also a Cosmic architecture that was to have a profound influence on the history of astrobiology. The story goes that only the master, Pythagoras, was graced with the gift of actually hearing this harmony of the spheres.
- Christian Huygens in: Mark Brake Alien Life Imagined: Communicating the Science and Culture of Astrobiology, Cambridge University Press, 8 November 2012, p. 8
- To the ancient eye, without the use of spyglass, only seven of these ‘wanderers’ or ‘planets’ as they were known, could be seen among the thousands of lights that bejewelled the firmament. The 'Wanderers' were different. True, like the fixed stars, the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn all seemed to revolve once a day around the Earth. But the Plants also had a peculiar motion.
- Christian Huygens in: "Alien Life Imagined: Communicating the Science and Culture of Astrobiology", p. 9
- ...cosmos was complete. Its out limit was the stellar sphere. Just inside was Saturn, since it was the planet that took longest to move around the Zodiac. Next came Jupiter and Mars, set in order of decreasing orbital period, the time taken to make one complete orbit about the central Earth. Innermost was the Moon, since the lunar orbit placed it closest to us. The remaining three planets of Sun, Venus and Mercury, posed a problem. All three vagabond stars made their seeming journey about the Earth, in the same common time of one year.
- Christian Huygens in: "Alien Life Imagined: Communicating the Science and Culture of Astrobiology", p. 11
- A similar situation occurred in astronomy, where the Newtonian law of gravitation had been found to predict the orbits of the outer planets with great accuracy, but had failed with the orbits of Mercury and Venus. The relativity theory of gravitation had provided the necessary modification of Newton's law, and in working out the details of the new theory, Einstein had utilized the fact that Newtonian law gave the right result at great distances from the sun. Heisenberg, confronted with a similar problem, was able to avail himself of the fact that the classical mechanics gave the right result at great distances from the atomic nucleus. Here, and here alone Heisenberg's theory made contact with the world of the older physics.
- But it is a very remarkable circumstance, that an acquaintance with the seven days of the week, so familiar from remote antiquity to the people who originally spoke Sanskrit language, though unknown to the Greeks and Romans, should have been preserved among the Germans. It is true, indeed, that among them the days received their names from their principal deities, and not merely from the planets, which, in Hindu mythology, are considered only as celestial beings of an inferior description. There seems, also, to be no doubt that Germans selected the names of the same planets to designate the days of the week, which have been immemorially used for the same purpose by the Hindus; and that, in both Germany and India, their consecutive order was the day of the Sun, the Moon, Mars, Mercury, Jupiter, Venus and Saturn.
- Vans Kennedy in: Researches Into the Nature and Affinity of Ancient and Hindu Mythology by Vans Kennedy, Longman, Rees, Orme, Brown and Green, 1831, p. 396-97
- The orbit of the earth is a circle; round the spheres to which this circle belongs describe a dodecahedron; the spheres including this will give the orbit of Mars. Round Mars describe a tetrahedron; the circle including this will be orbit of Jupiter. Describe a cube round Jupiter’s orbit; the circle including this will be Saturn. Now, inscribe in the earth’s orbit an icosahedron, the circle inscribed in it will be the orbit of Venus: inscribe an octahedron in the orbit of Venus: the circle inscribed in it will be Mercury’s orbit. This is the reason of number of planets.
- His thirty four circles or epicycles comprised four for the earth, three for the moon, seven for Mercury (on account of his highly eccentric orbit) and five each for the other planets.
- And while he was Euphorbus, he used to say that he [Pythagoras] had formerly been Aethalides, and that he had received as a gift from Mercury the perpetual transmigration of his soul, so that it was constantly transmigrating and passing into whatever plants or animals it pleased.
M - R
- Mercury is a small world of extreme temperatures, with a global magnetic field like Earth’s, but much weaker. Neither Venus nor Mars has such a magnetic field, although the two planets are similar to Earth in many other ways.
Venus, unlike the earth has a hellish temperature. Venus is farther from the Sun than Mercury but is even hotter. The high temperature is due to an extreme greenhouse effect, the process by which the atmospheric gases raise the temperature by absorbing outward flowing heat. Earth’s atmosphere may once have contained large amounts of carbon dioxide, the way Venus’s atmosphere does now. But on earth, the oceans absorbed much of carbon dioxide, so that gas could not trap as much heat in the atmosphere as it does on Venus.
The three large terrestrial planets are like the bowls of cereals in the child’s story of Goldilocks. Venus is too hot, Mars is too cold, but Earth is just right to support liquid water and life as we know it…
Venus is earth’s “evil twin”. It’s about the same size as earth, but with deadly heat and pressure, an unbreathable atmosphere, and highly acid rain
- Wide are the meadows of night
And daisies are shining there,
Tossing their lovely dews, Lustrous and fair;
And through these sweet fields go,
Wanderers amid the stars — Venus, Mercury, Uranus, Neptune, Saturn, Jupiter, Mars.
- The generalized theory of relativity has furnished still more remarkable results. This considers not only uniform but also accelerated motion. In particular, it is based on the impossibility of distinguishing acceleration from the gravitation or other force which produces it. Three consequences of the theory may be mentioned of which two have been confirmed while the third is still on trial: (1) It gives a correct explanation of the residual motion of forty-three seconds of arc per century of the perihelion of Mercury. (2) It predicts the deviation which a ray of light from a star should experience on passing near a large gravitating body, the sun, namely, 1".7. On Newton's corpuscular theory this should be only half as great. As a result of the measurements of the photographs of the eclipse of 1921 the number found was much nearer to the prediction of Einstein, and was inversely proportional to the distance from the center of the sun, in further confirmation of the theory. (3) The theory predicts a displacement of the [[solar spectral lines, and it seems that this prediction is also verified.
- Science is the part of NASA that's actually conducting interesting and scientifically important missions. Spacecraft sent to Mars, Saturn, Mercury, the Moon, comets, and asteroids have been making incredible discoveries, with more to come from recent launches to Jupiter, the Moon, and Mars. The country needs more of these robotic space exploration missions, not less.
- Mercury is one of the least-understood of the planets in our Solar System. Its distance from the Sun is just over one-third that of the Earth, and it contains a mass just 5½ percent that of Earth....Mercury has a weak magnetic field, about one percent as strong as Earth's… Mercury is so small that most scientists expected its core to have cooled and solidified long ago. Those scientists speculated that the magnetic field seen today may have been "frozen" into the planet when the core cooled.
- 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.
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.
4. The Moon.
5. The Sun.
- Plato in: The Classical Review, Volume 24 Plato’s Theory of Planets, Editors of the Observatory, 1904, p. 137
- Love seldom haunts the breast where learning lies, And Venus sets ere Mercury can rise.
S - Z
- Mercurial is relating to, or born under the planet Mercury. It is having qualities of eloquence, ingenuity, or thievishness attributed to the god Mercury or to the influence of the planet Mercury. It is characterized by rapid and unpredictable changeableness of mood [a mercurial temper] of, relating to, containing, or caused by Mercury.
Exploring Mercury: The Iron Planet
Robert G. Strom, Ann L. Sprague in: Exploring Mercury: The Iron Planet, Springer Science & Business Media, Jul 15, 2003
- Intercrater plains dominate Mercury's highlands. This image of the Mercurian highlands shows large areas of intercrater plains. The large scarp near the planet's limb is a thrust fault.
- In: p. xxii
- The Planet closest to the Sun is a beautiful sight, it shines brightly in the twilight sky. In our busy modern culture, most people know they can see Mercury with the naked eye only after a purposeful search, having found its location for the evening or morning from an astronomical source.
- In: p. 1
- Most ancient cultures were familiar with the twilight wanderers and guardian of the Sun. Because Mercury is closest planet to the Sun, its hurried orbit takes just 88 Earth days, and switches its appearance from east (morning twilight) to west (evening twilight) in the sky with a slightly variable period of about three months. Mercury also has an orbital plane that is tilted with respect to that of the Earth, so it also bobs up and down in the sky relative to the plane of the Earth and the Sun. Thus, it is sometimes lower than the Sun in declination and at other times it is higher. These two striking orbital peculiarities further contribute to Mercury's elusiveness....By far Mercury has been, most familiar to people living in equatorial and tropical latitudes, especially those with dry climates an clear skies.
- In: p. 1
- There is ample linguistic evidence that some of the first people to observe Mercury and commit the planet to the immortality of myth were Germanic people and Scandinavians who navigated far south from their native lands into what is now the Mediterranean and the coasts of Africa. Mercury was connected with the deity Woodan, or Odin among the northern seafarers. In Italy ancient people called Mercury Boudha, a word with the same origin as Woodan or Odin. The connection lives on in our current use of English day of week Wednesday derived from Woodan’s day.
- In: p. 2
- As seen from Earth, both Mercury and Venus stay close to the Sun because they orbit the Sun within the Earth's orbit. At their largest angular distance from the Sun as seen from Earth, they are at greatest elongation.
- In: p. 3
- The astronomical symbol of Mercury [☿] can be traced to a medieval Greek manuscript where it takes the form ?. The horizontal cross is a modern addition. The "horns" at the top of the symbol represent the wings of this speedy planet It is from the use of the name Hermes for Mercury that the usage of Hermean for characteristics of Mercury became popular during the 19th century and continues to be used by some today.
- In: p. 3
- In 1639 Giovanni Zupus discovered that Mercury went through phases like the Moon....These observations were profoundly significant because they were proof that the Copernican theory was correct and the earth was not at the center of the Universe.
- In: P.6
- Observations of the bright side of the Moon and Mercury were made with the airglow spectrometer and obtained the first and only measurements of Mercury in the EUV (extreme ultraviolet radiation). In addition, Venus, and hydrogen and helium radiation emanating from outside the Solar System were observed with the spectrometer.
- In: P.19
- The first pictures of Mercury were taken on 24 March 1974 from a distance of 5.5 million km...as Mariner 10 neared Mercury the images showed a heavily cratered surface superficially resembling the Moon’s.
- In: P.25
- Mercury's magnetic field was thought to be internally generated and similar in form to the Earth's field.
- In: P.34
- Mercury's orbit around the Sun is more elliptical than any other planet (Pluto is a Kuiper belt object). Its eccentricity, however, is still small enough that the orbit appears almost circular.
- In: P.40
- Temperatures on Mercury vary enormously. The planet is only is about 46 million km from the Sun at perihelion. At the equator, near the noon, the surface temperature reaches 427 degrees C (800 degrees F). At night just before sunrise, however, the temperature plunges to a frigid – 183 degrees C.
- In: P.43
- Mercury experiences the most extreme temperature range of any planet or satellite in the Solar System.
- In: P.44
- Mercury is the smallest planet in the Solar System (4,878 km diameter). Even three outer satellites are equal or larger than Mercury – Callisto (4,818 km diameter), Ganymede (another satellite of Jupiter) at 5,468 km diameter is significantly larger and the Saturnian's Satellite Titan (5,150 km diameter) is also larger. Mercury is only 4,878 km in diameter, or about one-third the diameter of the earth. Its volume is only about 6% that of the Earth, so it would take almost 18 Mercurys to make one Earth.
- In: P.47
- Although Mercury is small, it is very massive for its size (3.3x 1023 kg). Therefore, Mercury has almost the same surface gravity as the larger planet Mars.
- In: P.47
- Scientists strongly suspect that iron is the principal heavy element responsible for Mercury's high density. From this high density we can infer that the planet is composed of about 70% by weight of metallic iron and only 30% by weight of rocky material. Mercury thus contains more than twice as much iron per unit volume as any other planet or satellite in the Solar System.
- In: P.52
- Since Mercury rotates once every 58.6 Earth days and orbits the Sun in 87.9 Earth days, it rotates exactly three times as it circles the Sun twice.
- In: P.56
What Is the Planet Mercury?
- The Romans believed that gods and goddesses were in charge of everything on Earth. Mercury is named after the messenger for their gods. The Roman Mercury had wings on his helmet and shoes. He could travel very quickly from place to place. The planet Mercury moves quickly around the sun. That is how it got its name.
- Mercury is a little bigger than Earth's moon. It is made of heavier materials, like iron. But if you could weigh Mercury and the moon, Mercury would weigh a lot more. Mercury is heavy, but it is small. It would take more than 18 Mercurys to be as big as Earth.
- Earth has a blanket of air around it. Mercury does not. The blanket is what helps keep Earth from getting too hot or cold. Because it is so close to the sun, Mercury can be very hot. At night, Mercury gets very cold. We could not live on Mercury!
- Mercury is hard to study because it is so close to the sun. People have never gone to Mercury. Spacecraft without people have gone. Mariner 10 was the first to visit Mercury. It flew by in 1974 and 1975. Not even half of Mercury was seen then. After that, nothing was sent to Mercury for more than 30 years. NASA's MESSENGER spacecraft flew by Mercury in 2008 and 2009. In March 2011, it began to orbit Mercury. MESSENGER will study parts of Mercury that have not been seen before. It will let scientists learn many new things about the plane.
Mercury "Hollows" Found—Pits May Be Solar System First
NASA's MESSENGER spacecraft, David Blewett in: Rachel Kaufman Mercury "Hollows" Found—Pits May Be Solar System First, National Geographic News
- The planet Mercury is dotted with holes that appear to be unlike any other landform yet seen in the solar system. High-resolution photographs from NASA's MESSENGER spacecraft revealed the shallow, rimless, irregularly shaped depressions—similar to the holes in Swiss cheese—in impact craters all over Mercury.
- The features are widespread both in latitude and longitude. Dubbed hollows, the odd landforms can be tens of meters to a few kilometers wide, whereas the impact craters that contain them are tens of kilometers wide or bigger. The hollows are often seen in clusters on the walls, floors, and peaks of the craters. Many hollows have smooth, flat bottoms and feature highly reflective material...While Mercury had previously been thought of as a geologically dead planet, with few changes to it the hollows are much smaller than known volcanic pits, and the holes appear in places on Mercury that aren't likely to have experienced volcanic activity.
- The Martian depressions form as carbon-dioxide ice sublimates—turns directly from a solid to a gas—during seasonal temperature changes, hinting that some type of sublimation may be happening on Mercury. But on Mercury it's happening in solid rock, not in ice, so it's sort of a unique expression of geological processes that happen elsewhere, but maybe not as vigorously.
- ...that the hollows could form when volatile materials such as sulfur on the surface are exposed to the harsh solar wind—actually a stream of charged particles from the sun. Since the tiny planet has no atmosphere, these particles can hit the surface directly, vaporizing volatile minerals. Or the close sun's intense heat could "boil" the minerals away.
- ...using MESSENGER's x-ray spectrometer [it is] found that Mercury's surface has much more sulfur than that of any other rocky planet in the solar system.
- The old thinking was, Oh, Mercury, it's an old burned-out cinder and not so interesting. Now, here's this jaw-dropping thing that nobody ever predicted.