Neptune is the eighth and farthest planet from the Sun in the Solar System. It is the fourth-largest planet by diameter and the third-largest by mass. Among the gaseous planets in the Solar System, Neptune is the most dense. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times the mass of Earth but not as dense. Named after the Roman god of the sea, its astronomical symbol is ♆, a stylised version of the god Neptune's trident.
- Quotes are arranged alphabetically by author
- Neptune is dark, cold and whipped by supersonic winds. Neptune is the last of the hydrogen and helium gas giants in our solar system. More than 30 times as far from the Sun as Earth, the planet takes almost 165 Earth years to orbit our Sun. In 2011 Neptune completed its first orbit since its discovery in 1846.
- Things to know about Neptune are:
If the Sun were as tall as a typical front door, the Earth would be the size of a nickel and Neptune would be about as big as a baseball.
Neptune orbits our Sun, a star. Neptune is the eighth planet from the Sun at a distance of about 4.5 billion km (2.8 billion miles) or 30.07 AU.
One day on Neptune takes about 16 hours (the time it takes for Neptune to rotate or spin once). Neptune makes a complete orbit around the Sun (a year in Neptunian time) in about 165 Earth years (60,190 Earth days).
Neptune is a sister ice giant to Uranus. Neptune is mostly made of a very thick, very hot combination of water, ammonia, and methane over a possible heavier, approximately Earth-sized, solid core.
Neptune's atmosphere is made up mostly of hydrogen, helium (He) and methane.
Neptune has 13 confirmed moons (and 1 more awaiting official confirmation of discovery). Neptune's moons are named after various sea gods and nymphs in Greek mythology.
Neptune has six rings.
Voyager 2 is the only spacecraft to have visited Neptune.
Neptune cannot support life as we know it.
At times during the course of Neptune's orbit, dwarf planet Pluto is actually closer to the Sun, and us, than Neptune. This is due to the unusual elliptical (egg) shape of Pluto's orbit.
- National Aeronautics and Space Administration (NASA)in: “Neptune: Overview”
- Neptune was discovered by Urbain Le Verrier, John Couch Adams, and Johann Galle on 23 September 1846. It orbits around Sun 4.4983964 x 109 km away and is of 30.070 x Earth. Its Perihelion (closest) is 4.45975 x 109 km (2.981 x 101 A.U.), which is 30.318 x Earth. Its Aphelion (farthest) is 4.53704 x 109 km (3.033 x 101 A.U.), which is 29.830 x Earth. Neptune’s Sidereal Orbit Period (Length of Year) is 164.79132 Earth years, which is by comparison 164.791 x Earth. Its Orbit Circumference is 2.826 x 1010 km and by comparison 30.071 x Earth. It has an Average Orbit Velocity of 19,566 km/h (12,158 mph) which is 0.182 x Earth. Its Orbit Eccentricity is 0.00859048, which is 0.514 x Earth. It has an Orbit Inclination of 1.77 degrees. Its Equatorial Inclination to Orbit is 28.3 degrees. It has a Mean Radius of 2.4622 x 104 km, which is 3.8647 x Earth. Its Equatorial Circumference is 1.54705 x 105 km, which is 3.8647 x Earth. Its volume is 6.25257 x 1013 km3 and by comparison is 57.723 x Earth. Its mass is 1.0241 x 1026 kg, which is 17.148 x Earth. Its density is 1.638 g/cm3 , which is 0.297 x Earth. Its surface area is 7.6183 x 109 km2 and by comparison 14.980 x Earth. Its Surface Gravity is 11.15 m/s2 (36.6 ft/s2.) and by comparison if you weigh 100 pounds on Earth, you would weigh 114 pounds on Neptune. Its Escape Velocity is 2.356 x 104 m/s, which is by comparison: 2.105 x Earth. Its Sidereal Rotation Period (Length of Day) is 0.671 Earth days. The Effective Temperature on the planet is -214 °C (-353 °F) with the scientific notation of 59 K. The atmospheric constituents of Neptune are Hydrogen, Helium and Methane.
- The most common distinction made between the planets is “inner planets” versus outer “planets”. The term inner planets usually refers to the seven visual planets (although sometimes Jupiter and Saturn are not included in this list). This type of classification is very much a modern construct: before 1781, when Herschel discovered Uranus, there were only "inner" or "visible" planets—planets that were visible to the naked eye. (Of course the skies were a great deal clearer then). These included the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn. The outer planets are the planets that are only visible with a telescope: Uranus, Neptune and Pluto. The asteroid Chiron functions as a bridge between the inner and the outer planets....The fastest of the outer planets is Uranus which takes about 84 years to complete a cycle of the Zodiac. Today it is not unusual to see people to live past their Uranus return and humans are gradually developing a greater understanding of the energy of Uranus.
- Kevin Burk in: Astrology: Understanding the Birth Chart, Llewellyn Worldwide, 2001, p. 14
- 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.
- Although Uranus and Neptune are superficially twin planets, they are different enough to remind us - as do Venus and Earth - that we still have a lot to learn about the mix of natural laws and historical accidents that formed the planets and fashioned their destinies.
- Timothy Ferris in: Seeing in the Dark: How Amateur Astronomers Are Discovering the Wonders of the Universe,Simon and Schuster, 8 July 2003, p. 206
- 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.
- It is notorious that the same discovery is frequently made simultaneously and quite independently, by different persons. Thus, to speak of only a few cases in late years, the discoveries of photography, of electric telegraphy, and of the planet Neptune through theoretical calculations, have all their rival claimants. It would seem, that discoveries are usually made when the time is ripe for them—that is to say, when the ideas from which they naturally flow are fermenting in the minds of many men.
- We see it [the as-yet unseen, probable new planet, Neptune] as Columbus saw America from the coast 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.
- The remote Neptune is almost certainly as much the twin of Uranus in its general features as Saturn is of Jupiter.
- In: "The Living Age ..., Volume 169", p. 462
- The fact [is] that astronomers were able to predict the existence and location of Neptune, based on irregularities in the orbit of Uranus... Analysis of the orbital data of Uranus led to the conclusion that although the gravitational pull from Neptune accounted for 98% of the variation from the Uranus’s expected orbit, there were still unexplained irregularities.
- Karl F. Kuhn, Theo Koupelis in: In Quest of the Universe, Jones & Bartlett Learning, 1 January 2004, p. 325
- Neptune's atmosphere is revealed by Voyager 2 images to contain clouds of methane ice above a lower deck of hydrogen sulfide or ammonia ices, and to be dominated by an anticyclonic storm system designated the 'Great Dark Spot'; this bears both similarities and differences to the Great Red Spot of Jupiter. Like the rings of Uranus, those of Neptune are composed of very dark, but in addition very dusty, material. Six new regular satellites have been discovered whose radii range from 25 to 200 km. Triton is noted to be a differentiated body showing evidence of early surface-melting episodes. At least two active plumes are found on Triton, which may be driven by solar heating.
- B. A Smith, et al., in:Voyager 2 at Neptune - Imaging science results, Astronomy Abstract Service
- 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 inequalities.
- A species having a proboscis two or three inches longer could reach the nectar in the largest flowers of Angræcum sesquipedale, whose nectaries vary in length from ten to fourteen inches. That such a moth exists in Madagascar may be safely predicted; and naturalists who visit that island should search for it with as much confidence as astronomers searched for the planet Neptune - and they will be equally successful!
- Alfred Russel Wallace in: Journal of Science, and Annals of Astronomy, Biology, Geology ..., Volume 4, John Churchill and Sons, 1867, p. 477