The second planet (after Uranus) discovered in the “Modern Era” - Neptune - is the fourth largest and eighth planet at the distance from the Sun. He was named after the Roman sea god, similar to Poseidon among the Greeks. After the discovery of Uranus, scientists around the world began to argue, because... the trajectory of its orbit did not quite correspond to the universal law of gravity discovered by Newton.
This gave them the idea of the existence of another planet, not yet known, which influenced the orbit of the seventh planet with its gravitational field. 65 years after the discovery of Uranus, the planet Neptune was discovered on September 23, 1846. She was the first planet to be discovered using mathematical calculations rather than through long observations. The Englishman John Adams began calculations back in 1845, but they were not entirely correct. They were continued by Urbain Le Verrier, an astronomer and mathematician originally from France. He calculated the position of the planet with such accuracy that it was found on the very first evening of observations, so Le Verrier began to be considered the discoverer of the planet. The British protested and after much debate, everyone recognized Adams's considerable contribution, and he is also considered the discoverer of Neptune. It was a breakthrough in computational astronomy! Until 1930, Neptune was considered the most distant and last planet. The discovery of Pluto made it the second to last. But in 2006, the IAU, the International Astronomical Union, adopted a more precise formulation of the definition of “planet”, and Pluto began to be considered a “dwarf planet”, and Neptune again became the last planet of our solar system.
Structure of Neptune
The characteristics of Neptune were obtained using only one spacecraft, Voyager 2. All photographs were taken from him. In 1989, he passed 4.5 thousand km from the planet, discovering several new satellites and recording a “Great Dark Spot”, similar to the “Red Spot” on Jupiter.
The structure of Neptune in its composition is very close to Uranus. It is also a gaseous planet with a solid core, approximately the same mass as the Earth and a temperature similar to the surface of the Sun - up to 7000 K. Moreover, the total mass of Neptune is approximately 17 times the mass of the Earth. The core of the eighth planet is enveloped in a mantle of water, methane ice and ammonia. Next comes the atmosphere, it includes 80% hydrogen, 19% helium and about 1% methane. The upper clouds of the planet also consist of methane, which absorb the red spectrum of the sun's rays, so blue dominates the color of the planet. The temperature of the upper layers is – 200 °C. Neptune's atmosphere has the strongest winds of any known planet. Their speed can reach 2100 km/h! Located at a distance of 30 a. That is, a full revolution around the Sun takes Neptune almost 165 Earth years, therefore, since its discovery, it will make its first full revolution only in 2011.
Moons of Neptune
William Lassell discovered the largest moon, Triton, just a couple of weeks after the discovery of Neptune itself. Its density is 2 g/cm³, therefore, in mass it exceeds by 99% all the satellites of the planet. Although its size is slightly larger than the Moon.
It has a retrograde orbit and most likely, a very long time ago, was captured by Neptune's field from the nearby Kuiper belt. This field constantly pulls the satellite closer and closer to the planet. Therefore, in the near future, by cosmic standards (in 100 million years), it will collide with Neptune, as a result of which rings may form that are more powerful and noticeable than those currently observed around Saturn. Triton has an atmosphere, which could mean there is a liquid ocean beneath the icy crust at the edge of the surface. Because Neptune in Roman mythology was a sea god, all of his moons are named after Roman sea gods of lesser rank. Among them are Nereid, Proteus, Despina, Talasa and Galatea. The mass of all these satellites is less than 1% of the mass of Triton!
Characteristics of Neptune
Mass: 1.025 * 1026 kg (17 times more than Earth)
Diameter at equator: 49,528 km (3.9 times larger than Earth)
Diameter at the pole: 48680 km
Axle tilt: 28.3°
Density: 1.64 g/cm³
Temperature of the upper layers: about – 200 °C
Period of revolution around the axis (days): 15 hours 58 minutes
Distance from the Sun (average): 30 a. e. or 4.5 billion km
Orbital period around the Sun (year): 165 years
Orbital speed: 5.4 km/s
Orbital eccentricity: e = 0.011
Orbital inclination to the ecliptic: i = 1.77°
Gravity acceleration: 11 m/s²
Satellites: there are 13 pieces.
Although, of course, the word “giant” will be a little strong in relation to Neptune, a planet that, although very large by cosmic standards, is, nevertheless, significantly inferior in size to our other giant planets: Saturn, Saturn, etc. Speaking of Uranus, although this planet is larger in size than Neptune, Neptune is still 18% larger in mass than Uranus. In general, this planet, named because of its blue color in honor of the ancient god of the seas, Neptune can be considered the smallest of the giant planets and at the same time the most massive - Neptune’s density is many times stronger than that of other planets. But compared to Neptune and our Earth, they are tiny, if you imagine that our Sun is the size of a door, then the Earth is the size of a coin, and Neptune is the same in size as a large baseball.
The history of the discovery of the planet Neptune
The history of the discovery of Neptune is unique in its kind, since it is the first planet in our solar system that was discovered purely theoretically, thanks to mathematical calculations, and only then was it noticed through a telescope. It happened like this: back in 1846, French astronomer Alexis Bouvard observed the movement of the planet Uranus through a telescope and noticed strange deviations in its orbit. The anomaly in the movement of the planet, in his opinion, could be caused by the strong gravitational influence of some other large celestial body. Alexis’s German colleague, astronomer Johann Halle, made the necessary mathematical calculations to determine the location of this previously unknown planet, and they turned out to be correct - soon our Neptune was discovered at the site of the supposed location of the unknown “Planet X”.
Although long before this, the planet Neptune was observed in a telescope by the great. True, in his astronomical notes he noted it as a star, not a planet, so the discovery was not credited to him.
Neptune is the most distant planet in the solar system
“But what about?”, you probably ask. In fact, everything here is not as simple as it seems at first glance. Since its discovery in 1846, Neptune has rightfully been considered the farthest planet from the Sun. But in 1930, little Pluto was discovered, which is even further away. There’s just one nuance here: Pluto’s orbit is strongly elongated along an ellipse in such a way that at certain moments of its movement Pluto is closer to the Sun than Neptune. The last time such an astronomical phenomenon occurred was from 1978 to 1999 - for 20 years, Neptune again had the title of the full-fledged “farthest planet from the Sun.”
Some astronomers, in order to get rid of these confusions, even proposed to “demote” Pluto from the title of planet, they say, it is just a small celestial body flying in orbit, or to assign the status of a “dwarf planet”, however, disputes on this matter are still ongoing.
Features of the planet Neptune
Neptune has its bright blue appearance due to the strong density of clouds in the planet’s atmosphere; these clouds conceal chemical compounds that are still completely unknown to our science, which, when absorbed from sunlight, turn blue. One year on Neptune is equal to our 165 years, which is the time it takes Neptune to complete its full cycle in its orbit around the Sun. But a day on Neptune is not as long as a year; it is even shorter than ours on Earth, since it lasts only 16 hours.
Neptune temperature
Since the sun’s rays reach the distant “blue giant” in very small quantities, it is natural that it is very, very cold on its surface - the average surface temperature there is -221 degrees Celsius, which is two times lower than the freezing point of water. In a word, if you were on Neptune, you would turn into ice in the blink of an eye.
Surface of Neptune
Neptune's surface consists of ammonia and methane ice, but the planet's core may well turn out to be rock, but this is still just a hypothesis. It is curious that the force of gravity on Neptune is very similar to that of Earth, it is only 17% greater than ours, and this despite the fact that Neptune is 17 times larger than Earth. Despite this, we are unlikely to be able to walk around Neptune in the near future, see the previous paragraph about the ice. And besides, strong winds blow on the surface of Neptune, the speed of which can reach up to 2400 kilometers per hour (!), perhaps on no other planet in our solar system there are such strong winds as here.
Neptune size
As mentioned above, it is 17 times larger than our Earth. The picture below shows a comparison of the sizes of our planets.
Atmosphere of Neptune
The composition of Neptune's atmosphere is similar to the atmospheres of most similar giant planets: it is mainly dominated by hydrogen and helium atoms, and also contains small amounts of ammonia, frozen water, methane and other chemical elements. But unlike other large planets, Neptune’s atmosphere contains a lot of ice, which is due to its remote position.
Rings of the planet Neptune
Surely when you hear about planetary rings, Saturn immediately comes to mind, but in fact, it is far from the only owner of rings. Our Neptune also has rings, although not as large and beautiful as those of the planet. Neptune has five rings in total, named after the astronomers who discovered them: Halle, Le Verrier, Lascelles, Arago and Adams.
Neptune's rings consist of small pebbles and cosmic dust (many micron-sized particles), their structure is somewhat similar to the rings of Jupiter and they are quite difficult to notice, since they are black. Scientists believe that Neptune's rings are relatively young, at least much younger than the rings of its neighbor Uranus.
Moons of Neptune
Neptune, like any decent giant planet, has its own satellites, not just one, but thirteen, named after the smaller sea gods of the ancient pantheon.
Particularly interesting is the satellite Triton, discovered, in part, thanks to... beer. The fact is that the English astronomer William Lasing, who actually discovered Triton, made a large fortune by brewing and trading beer, which subsequently allowed him to invest a lot of money and time in his favorite hobby - astronomy (especially since it is not cheap to equip a high-quality observatory).
But what is interesting and unique about Triton? The fact is that this is the only known satellite in our solar system that rotates around the planet in the opposite direction relative to the rotation of the planet itself. In scientific terminology, this is called “retrograde orbit.” Scientists suggest that Triton was not previously a satellite at all, but an independent dwarf planet (like Pluto), which, by the will of fate, fell into the sphere of influence of Neptune’s gravity, essentially captured by the “blue giant.” But it doesn't end there: Neptune's gravity pulls Triton closer and closer, and after several million light years, gravitational forces can tear the satellite apart.
How long does it take to fly to Neptune?
For a long time. This is in short, with modern technology, of course. After all, the distance from Neptune to the Sun is 4.5 billion kilometers, and the distance from Earth to Neptune is 4.3 billion kilometers, respectively. The only satellite sent from Earth to Neptune, Voyager 2, launched in 1977, reached its destination only in 1989, where it photographed the “large dark spot” on the surface of Neptune and observed a number of powerful storms in the planet’s atmosphere.
Planet Neptune video
And at the end of our article, we offer you an interesting video about the planet Neptune.
Neptune compared to our planet
To really understand how big Neptune is, in fact, it can be compared to another planet, for convenience, we can take our planet for these purposes.
Comparison of the sizes of Earth and Neptune
First, let's look at the sizes of the planets being compared. The diameter of the gas giant is about 49,500 km. This makes it the fourth largest planet in the solar system. Compared to our planet, it is 3.9 times larger.
Its mass is 1.02 x 10*26 kg. It turns out that it is 17 times larger in mass than our home planet.
What about volume? Its volume is 6.3 x 10 * 13 km 3. We could fit 57 planets like ours inside it and still have room left. Our day lasts 24 hours, and the day on the gas giant lasts 16 hours and 6 minutes. A year accordingly lasts 164.79 years.
Many parameters of our planets vary greatly, with the possible exception of one thing: the force of gravity.
The gravity on Neptune (assuming the planet has a hypothetical surface) is only 14% stronger than the gravity on Earth.
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Voyager 2 took this image of Neptune five days before its historic flyby of the planet on August 25, 1989.
The planet Neptune is a mysterious blue giant on the outskirts of the solar system, whose existence was not suspected until the end of the first half of the 19th century.
A distant planet, invisible without optical instruments, was discovered in the fall of 1846. J. C. Adams was the first to think about the existence of a celestial body that anomalously affects the movement. He presented his calculations and assumptions to the royal astronomer Erie, who ignored them. At the same time, the Frenchman Le Verrier was studying deviations in the orbit of Uranus; his conclusions about the existence of an unknown planet were presented in 1845. It was obvious that the results of the two independent studies were very similar.
In September 1846, an unknown planet was spotted through the telescope of the Berlin Observatory, located at the location indicated in Le Verrier's calculations. The discovery, made using mathematical calculations, shocked the scientific world and became the subject of a dispute between England and France about national priority. To avoid disputes, the German astronomer Halle, who examined the new planet through a telescope, can be considered the discoverer. According to tradition, the name of one of the Roman gods, the patron saint of the seas, Neptune, was chosen for the name.
Neptune's orbit
After Pluto from the list of planets, Neptune turned out to be the last - eighth - representative of the solar system. Its distance from the center is 4.5 billion km; it takes a wave of light 4 hours to travel this distance. The planet, along with Saturn, Uranus and Jupiter, was included in the group of four gas giants. Due to the enormous diameter of the orbit, a year here is equal to 164.8 Earth years, and a day passes in less than 16 hours. The trajectory around the Sun is close to circular, its eccentricity is 0.0112.
Planet structure
Mathematical calculations made it possible to create a theoretical model of the structure of Neptune. In its center there is a solid core, similar in mass to the Earth; iron, silicates, and nickel are found in its composition. The surface looks like a viscous mass of ammonia, water and methane modifications of ice, which flows into the atmosphere without a clear boundary. The internal temperature of the core is quite high - reaching 7000 degrees - but due to the high pressure, the frozen surface does not melt. Neptune's is 17 times higher than Earth's and is 1.0243x10 in 26 kg.
Atmosphere and raging winds
The base is: hydrogen – 82%, helium – 15% and methane – 1%. This is a traditional composition for gas giants. The temperature on the conventional surface of Neptune shows -220 degrees Celsius. In the lower layers of the atmosphere, clouds formed by crystals of methane, hydrogen sulfide, ammonia or ammonium sulfide have been observed. It's these pieces of ice that create the blue glow around the planet, but that's only part of the explanation. There is a hypothesis about an unknown substance that gives a bright blue color.
The winds blowing on Neptune have a unique speed, its average is 1000 km/h, and hurricane gusts reach 2400 km/h. Air masses move against the planet's axis of rotation. An inexplicable fact is the increase in storms and winds, which is observed with increasing distance between the planet and the Sun.
The "" spacecraft and the Hubble telescope observed an amazing phenomenon - the Great Dark Spot - a hurricane of epic proportions that rushed across Neptune at a speed of 1000 km/h. Similar vortices appear and disappear in different places on the planet.
Magnetosphere
The giant's magnetic field has gained significant power; its basis is considered to be a conductive liquid mantle. A displacement of the magnetic axis relative to the geographic axis by 47 degrees causes the magnetosphere to change its shape following the rotation of the planet. This mighty shield reflects the energy of the solar wind.
Moons of Neptune
The satellite, Triton, was spotted a month after the grand discovery of Neptune. Its mass is equal to 99% of the entire satellite system. The appearance of Triton is associated with a possible capture from.
The Kuiper Belt is a vast region filled with objects the size of small satellites, but there are a few as large as Pluto and some perhaps even larger. Behind the Kuiper Belt is the place from which comets come to us. The Oort cloud extends almost halfway to the nearest star.
Triton is one of three moons in our system that has an atmosphere. Triton is the only one with a spherical shape. In total, in the company of Neptune there are 14 celestial bodies, named after the smaller gods of the sea depths.
Since the discovery of the planet, the presence of it has been discussed, but no confirmation of the theory has been found. It was only in 1984 that a bright arc was noticed at a Chilean observatory. The remaining five rings were found thanks to research by Voyager 2. The formations are dark in color and do not reflect sunlight. They owe their names to the people who discovered Neptune: Halle, Le Verrier, Argo, Lascelles, and the most distant and unusual one is named after Adams. This ring is made up of separate arms that should have merged into a single structure, but don't. A possible reason is considered to be the effect of gravity on undiscovered satellites. One formation remains nameless.
Research
Neptune's enormous distance from Earth and its special location in space make observing the planet difficult. The advent of large telescopes with powerful optics has expanded the capabilities of scientists. All studies of Neptune are based on data obtained by the Voyager 2 mission. The distant blue planet, flying at the edge of the world we know, is full of things about which we still know practically nothing.
New Horizons captures Neptune and its moon Triton. The image was taken on July 10, 2014 from a distance of 3.96 billion kilometers.
Images of Neptune
Voyager 2's images of Neptune and its moons are largely underappreciated. More fascinating than even Neptune itself is its giant moon Triton, which is similar in size and density to Pluto. Triton may have been captured by Neptune, as evidenced by its retrograde (clockwise) orbit around Neptune. The gravitational interaction between the satellite and the planet generates heat and keeps Triton active. Its surface has several craters and is geologically active.
Its rings are thin and weak and almost invisible from Earth. Voyager 2 took the photo while they were backlit by the Sun. The image is severely overexposed (10 minutes).
Neptune clouds
Despite its great distance from the Sun, Neptune has highly dynamic weather, including some of the strongest winds in the Solar System. The "Great Dark Spot" seen in the image has already disappeared and shows us how quickly changes are happening on the most distant planet.
The most complete map of Triton to date
Paul Schenk from the Lunar and Planetary Institute (Houston, USA) reworked old Voyager data to reveal more details. The result is a map of both hemispheres, although much of the Northern Hemisphere is missing because it was in shadow when the probe flew by.
Animation of the Voyager 2 spacecraft flying past Triton a, committed in 1989. During the flyby, most of the Northern Hemisphere Triton but was in the shadows. Due to Voyager's high speed and slow rotation Triton oh, we could only see one hemisphere.
Geysers of Triton
Since it is one of the planets that cannot be seen with the naked eye, Neptune was discovered relatively recently. Considering the distance to it, it was observed very close once - in 1989 by the Voyager 2 spacecraft. However, what we learned about this gas (and ice) giant at that time revealed many secrets and the history of its formation.
Opening and Naming:
The discovery of Neptune took place in the 19th century, although there is evidence that it occurred long before that. For example, Galileo Galilei's drawings of December 28, 1612 and January 27, 1613 contained plotted points that are now known to correspond to the location of Neptune on those dates. However, in both cases, Galileo mistook the planet for .
In 1821, French astronomer Alexis Bouvard published astronomical tables. Subsequent observations showed significant deviations from the tables that Bouvard provided, suggesting that an unknown celestial body was disturbing the orbit of Uranus through gravitational interaction.
The new Berlin Observatory on Linden Street, where the planet Neptune was experimentally discovered. Courtesy: Leibniz-Institute for Astrophysics Potsdam.
In 1843, English astronomer John Couch Adams began his work to study the orbit of Uranus using the data he had obtained and made several different estimates of the planet's orbit for the coming years. In 1845 - 1846, Urban Le Verrier, independently of Adams, carried out his own calculations, which he shared with Johann Gottfried Halle of the Berlin Observatory. Galle confirmed the presence of the planet using coordinates given by Le Verrier on September 23, 1846.
The announcement of the discovery was met with controversy, since Le Verrier and Adams also claimed to be the discoverers. Ultimately, an international consensus was reached in which Le Verrier and Adams were jointly recognized for their contributions to the discovery. However, a re-evaluation by historians of the relevant historical documents in 1998 led to the conclusion that Le Verrier was directly responsible for the discovery and deserved a larger share of the contribution to the discovery.
Claiming his rights to the discovery, Le Verrier proposed naming the planet after himself, but this met with stiff resistance outside France. He also proposed the name Neptune, which was eventually accepted by the international community. This was largely because it was consistent with the nomenclature of other planets, all of which were named after deities from Greco-Roman mythology.
Size, mass and orbit of Neptune:
With an average radius of 24.622 ± 19 km, Neptune is the fourth largest planet in the Solar System and is in . But with a mass of 1.0243 x 10 26 kg, which is 17 times the mass of Earth, it is the third most massive planet, ahead of Uranus. The planet has a very slight orbital eccentricity of 0.0086 and the orbital radius at perihelion is 29.81 astronomical units (4.459 x 10 9 km), and at aphelion 30.33 astronomical units (4.537 x 10 9 km).
Comparison of the sizes of Neptune and Earth. Credit: NASA
The planet Neptune takes 16 hours 6 minutes 36 seconds (0.6713 Earth days) to complete one revolution on its axis (one sidereal rotation), and 164.8 Earth years to complete one orbit around the Sun. This means that a day on Neptune lasts 67% of an Earth day, while a Neptunian year is equivalent to approximately 60,190 Earth days (or 89,666 Neptunian days).
Since Neptune's axial tilt (28.32°) is similar to the Earth's axial tilt (~23°) and (~25°), the planet experiences seasonal climate changes. Combined with its long orbital period, this means that Neptune's seasons last 40 Earth years. Also due to its axial tilt comparable to Earth's, the fact is that the variation in day length throughout the year is no more extreme than on Earth.
Neptune's orbit also has a strong influence on the region behind its orbit known as the Kuiper Belt (also called the "trans-Neptunian belt"). In much the same way it dominates, shaping its structure, as Neptune's gravity dominates the Kuiper Belt. During the existence of the Solar System, some regions of the Kuiper Belt were destabilized by the gravity of the planet Neptune, creating gaps in the structure of the Kuiper Belt.
Also within these empty regions are orbits containing objects with an age equal to . These resonances occur when Neptune's orbital period is an exact fraction of the object's orbital period, meaning that they complete part of the orbit during Neptune's full orbit. The most populous resonance in the Kuiper Belt, with over 200 objects, is the 2:3 resonance.
Objects in this resonance travel 2 orbits for every 3 orbits of Neptune and are called plutinos because the largest known is among them. Although Pluto regularly crosses Neptune's orbit, they can never collide due to the 2:3 resonance.
The planet Neptune has a number of known Trojan objects occupying the L4 and L5 Lagrange points - regions of gravitational stability in front of and behind Neptune in its orbit. Some Neptune Trojans have remarkably stable orbits, and were likely formed with Neptune rather than captured by it.
Composition of the planet Neptune:
Because of its smaller size and higher concentrations of volatiles compared to Jupiter and Saturn, the planet Neptune (much like Uranus) is often called an ice giant, a subclass of the giant planets. Just like Uranus, Neptune's internal structure can be roughly divided into different layers: a rocky core consisting of silicates and metals, a mantle containing water, ammonia and methane in the form of ice, and an atmosphere consisting of hydrogen, helium and methane gases.
Neptune's core is made of iron, nickel and silicates, and scientists believe it contains 1.2 times the mass of Earth. The pressure at the center of the core, according to scientists, is 7 Mbar (700 GPa), twice as high as at the center of the Earth, and temperatures at the center of the planet Pluto reach 5400 Kelvin. At a depth of 7,000 km, conditions may be such that methane is converted into diamond crystals that fall as rocks.
The mantle contains 10-15 Earth masses and is rich in water, ammonia and methane. This mixture is called ice, although it is actually a hot, dense liquid, and is sometimes called an "ammonia water ocean." Meanwhile, the atmosphere contains 5-10% of the planet's mass and extends 10-20% towards the core, where it reaches a pressure of about 10 GPa - 100,000 times the pressure of Earth's atmosphere.
Internal structure of the planet Neptune. Credit: NASA
Elevated concentrations of methane, ammonia and water were found in the lower atmosphere. Unlike Uranus, the planet Neptune has a larger ocean inside, while Uranus has a smaller mantle.
Atmosphere of the planet Neptune:
At high altitudes, Neptune's atmosphere is 80% hydrogen and 19% helium, with traces of methane. Like Uranus, absorption of red light by atmospheric methane is part of what gives Neptune its blue hue, although Neptune is darker and brighter. Since Neptune is similar to Uranus in terms of methane content in the atmosphere, scientists believe that some unknown atmospheric component contributes to a more intense color of Neptune.
Neptune's atmosphere is divided into two main regions: the lower troposphere, where the temperature decreases with altitude, and the stratosphere, where the pressure reaches 0.1 bar (10 kPa). The stratosphere is then replaced by the thermosphere with a pressure of 10 -5 - 10 -4 bar (1-10 Pa), which gradually turns into the exosphere.
Spectral analysis of Neptune suggests that its lower stratosphere is hazy due to the condensation of products of the interaction of ultraviolet radiation and methane (photolysis), which creates ethane and acetylene compounds. The stratosphere also contains trace amounts of carbon monoxide and cyanide, which are responsible for the fact that the stratosphere of the planet Neptune is warmer than the stratosphere of the planet Uranus.
A contrasting image in altered colors, emphasizing the features of Neptune's atmosphere, including wind speed. Credit: Erich Karkoschka.
For reasons that remain unclear, the planet's thermosphere has an unusually high temperature of about 750 Kelvin (476.85 °C). The planet is too far from the Sun for this heat to be generated by its ultraviolet radiation, which means another heating mechanism is involved, which could be the interaction of the atmosphere with ions in the planet's magnetic field or gravitational waves from inside the planet that dissipate into the atmosphere.
Since Neptune is not a solid body, its atmosphere is subject to differential rotation. The broad equatorial zone rotates with a period of about 18 hours, which is slower than the 16.1-hour rotation of the planet's magnetic field. On the contrary, the opposite trend is observed in the polar regions, where the rotation period is 12 hours.
This differential rotation is the most pronounced of any planet in the Solar System and results in strong latitudinal wind shears and destructive storms. Three of the most spectacular storms were spotted in 1989 by the Voyager 2 space probe and then named based on their appearance.
The first of these was a massive anticyclone measuring 13,000 x 6,600 km and resembling Jupiter's Great Red Spot. Called the Great Dark Spot, this storm was no longer detected 5 years later (November 2, 1994), when the Hubble Space Telescope looked at the planet. Instead, a new storm, very similar to the previous one, was discovered in the planet's northern hemisphere, suggesting that these storms have a shorter lifespan than storms on Jupiter.
Reconstruction of Voyager 2 images showing the Great Dark Spot (top left), Scooter (middle), and the Lesser Dark Spot (lower right). Credit: NASA/JPL.
Scooter is another storm, a group of white clouds located further south of the Great Dark Spot. The nickname first appeared during the months Voyager 2 spent near the planet in 1989, when it observed a group of clouds moving at speeds faster than the Great Dark Spot.
The Lesser Dark Spot, a southern cyclone, was the second most intense Neptune storm observed in 1989. Initially it was completely dark, but as Voyager 2 approached the planet, a bright core developed and could be seen in the highest resolution images.
Moons of the planet Neptune:
Neptune has 14 known natural satellites (moons), all but one are named after Greco-Roman sea deities (S/2004 N 1 is not currently named). These satellites are divided into two groups - regular and irregular satellites - based on their orbit and proximity to Neptune. Neptune's regular satellites are Naiad, Thalassa, Despina, Galatea, Larissa, S/2004 N 1 and Proteus. These satellites are the closest to the planet and move in circular orbits in the direction of motion around their Neptune axis and lie in the equatorial plane of the planet.
They extend from 48,227 km (Niad) to 117,646 km (Proteus) from Neptune, and all but the two outermost ones, S/2004 N 1 and Proteus, move in their orbits slower than the orbital period of 0.6713 Earth days. Based on observational data and estimated densities, these satellites range in size and mass from 96 x 60 x 52 km and 1.9 x 10^17 kg (Naiad) to 436 x 416 x 402 km and 50.35 x 10^ 17 kg (Proteus).
This composite image from the Hubble Space Telescope shows the location of the newly discovered moon, designated S/2004 N 1, in orbit around the giant planet Neptune, 4.8 billion kilometers from Earth. Credit: NASA, ESA, and M. Showalter (SETI Institute).
With the exception of Larissa and Proteus, which are the most round, all of Neptune's inner moons are elongated. Their spectrum indicates that they are composed of water ice contaminated with darker material, likely organic compounds. In this regard, Neptune's inner moons are very similar to the moons of Uranus.
Neptune's remaining moons are irregular moons, including Triton. They mainly move in inclined eccentric and often retrograde orbits (against the planet's rotation on its axis) away from Neptune. The only exception is Triton, which orbits closer to the planet and moves in a circular orbit, albeit retrograde and inclined.
In order of distance from the planet, the irregular satellites are Triton, Nereid, Halimeda, Sao, Laomedea, Neso and Psamapha - a group that includes retrograde and prograde (moving in the same direction as the attracting celestial body) objects. With the exception of Triton and Nereid, Neptune's irregular moons are similar to those of other giant planets and are believed to have been gravitationally captured in the past.
In terms of size and mass, the irregular satellites are similar, ranging from approximately 40 km in diameter and a mass of 4 x 10^16 kg (Psamapha) to 62 km and 16 x 10^16 kg (Halimeda). Triton and Nereid are unusual irregular moons and are therefore treated separately from Neptune's five other irregular moons. Four differences are noted between these two and other irregular satellites.
First of all, they are the two largest irregular satellites in the Solar System. Triton is almost an order of magnitude larger than all other known irregular satellites and contains more than 99.5% of the mass of all known satellites orbiting Neptune, including the planet's rings and 13 other known satellites.
Color mosaic image of Triton taken by Voyager 2 in 1989. Credit: NASA/JPL/USGS.
Secondly, they both have atypically small semi-major axes; Triton has an order of magnitude smaller in magnitude than other known irregular satellites. Third, they both have unusual orbital eccentricities: Nereid has one of the most eccentric orbits of any known irregular satellite, while Triton's orbit is almost circular. Finally, Nereid has the lowest orbital inclination of any known irregular satellite.
With an average diameter of about 2,700 km and a mass of 214,080 ± 520 x 10^17 kg, Triton is Neptune's largest moon, and the only one large enough to achieve hydrostatic equilibrium (that is, a spherical shape). Triton is located at a distance of 354,759 km from Neptune between the inner and outer satellites.
Triton moves in a retrograde quasi-circular orbit and is mainly composed of ices of nitrogen, methane, carbon dioxide and water. With a geometric albedo of over 70% and a Bond albedo of 90%, this satellite is one of the brightest objects in the Solar System. Its surface has a reddish tint, due to the interaction of ultraviolet radiation and methane, resulting in the creation of tholins (organic substances in the spectra of the icy bodies of our Solar System).
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- Size N.
- Radius N.
- Temperature N.
- N. compared to Earth
- How long is a day on N.?
- Distance from Earth to N.
- Orbit N.
- How long is a year in N.?
- How long does it take for Earth to complete one revolution around the Sun?
- Distance from the Sun to N.
- How many moons (natural satellites) does N. have?
- Rings N.
- Nereid
- Triton
- Naiad
- Who discovered N.?
- How did N. get its name?
- Symbol N.
- Atmosphere N.
- Tsvet N.
- Weather on N.
- Surface N.
- Collection of photographs N.
- Life on N.
- 10 interesting facts about N.
- Pluto and N.
- Uranus and N.
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