Structure of Neptune, according to NASA. Authors and peahen: NASA.
Being a gas giant (or ice giant), Neptune does not have a solid surface. As you know, the blue-green disk that we all saw in NASA photographs is not the surface of the planet. What we see are actually the tops of very deep gas clouds, and if a person tried to stand on one of these peaks, he would simply begin to fall through the gas layers of the planet. During this fall, he would experience a continuous increase in temperature and pressure until he finally reached the “solid” core. This will be the surface, which (as in the case of other gas giants) is defined in astronomy as a point in the atmosphere where the pressure reaches one bar. Neptune's surface is one of the most active and dynamic places in our entire solar system.
The planet's average radius is 24,622 ± 19 kilometers, making Neptune the fourth largest planet in the Solar System. But with a mass of 1.0243*10 26 kilograms - which is about 17 times the mass of Earth - it is the third most massive planet in our system. Due to its smaller size and higher concentrations of volatiles relative to Jupiter and Saturn, Neptune (like Uranus) is often called an ice giant, a subclass of giant gas planets.
As with Uranus, the absorption of red light by the methane in the atmosphere causes Neptune to appear blue. Since the amount of methane in Neptune's atmosphere is almost similar to that of Uranus, there is likely some unknown component that is responsible for Neptune's brighter color.
Neptune's atmosphere can be divided into two main regions: the troposphere, where temperature decreases with altitude; and the stratosphere, where temperature increases with altitude. In the troposphere, pressure ranges from one to five bar (100 and 500 kPa), therefore, the “surface” of Neptune is located within this region. Therefore, we can say that the “surface” of Neptune consists of 80% hydrogen and 19% helium. The upper layer of the atmosphere is penetrated by moving bands of clouds that have different compositions depending on altitude and pressure. At the upper level, temperatures are suitable for methane to condense; the clouds here consist of ammonia, ammonium sulfide, hydrogen sulfide and water.
The image of Neptune on the left was taken during testing of the adaptive optics instrument MUSE mounted on the VLT. The image on the right is from the Hubble Space Telescope. Note that both images were acquired at different times. Credit: ESO/P. Weilbacher, AIP/NASA/ESA/MH Wong & J. Tollefson, UC Berkeley. At lower levels, it is believed clouds of ammonia and hydrogen sulfide may also exist. In the lower regions of the troposphere, where the pressure is about 50 bar (5 MPa) and the temperature is 273 K (0 °C), clouds consisting of water ice should be located.
Because Neptune is not a solid body, its atmosphere undergoes differential rotation. Thus, the equatorial zone rotates with a period of about 18 hours, and the rotation period of the polar regions does not exceed 12 hours. This differential rotation is more pronounced than that of any other planet in the solar system, and it results in the presence of very strong winds and storms. The three most impressive of them were spotted in 1989 by the Voyager 2 space probe. The largest storm reached 13,000 kilometers in length and 6,600 kilometers in width, which is comparable to the size of the Great Red Spot on Jupiter. Unfortunately, known as the Great Dark Spot, this storm was not spotted five years later when researchers searched for it using the Hubble Space Telescope.
For reasons that are still unknown to astronomers, Neptune is unusually hot. Despite the fact that this planet is much further from the Sun than Uranus and receives 40% less sunlight, the temperature at its surface is approximately equal to that of Uranus. In fact, Neptune emits 2.6 times more energy than it receives from the Sun.
Such a large amount of internal heat, bordering on the cold of outer space, creates a huge temperature difference. And this causes super-fast winds to appear on Neptune. The maximum wind speed on Jupiter can reach 500 km/h. This is twice the speed of the most powerful hurricanes on Earth. But this is nothing compared to Neptune. Astronomers have calculated that winds on Neptune can reach 2,100 km/h.
Deep inside Neptune may still have a really hard surface, but the temperature in that area will be thousands of degrees, which is enough to melt the rock. Thus, it is not possible to stand on the “surface” of Neptune, let alone walk on it.
BASIC DATA ABOUT NEPTUNE
Neptune is primarily a giant of gas and ice.
Neptune is the eighth planet of the solar system.
Neptune is the farthest planet from the Sun since Pluto was demoted to the rank of dwarf planet.
Scientists don't know how clouds can move so fast on a cold, icy planet like Neptune. They suggest that cold temperatures and the flow of liquid gases in the planet's atmosphere may reduce friction enough to allow winds to pick up significant speeds.
Of all the planets in our system, Neptune is the coldest.
The upper layers of the planet's atmosphere have a temperature of -223 degrees Celsius.
Neptune produces more heat than it receives from the Sun.
Neptune's atmosphere is dominated by chemical elements such as hydrogen, methane and helium.
Neptune's atmosphere smoothly transitions into a liquid ocean, and that into a frozen mantle. This planet has no surface as such.
Presumably, Neptune has a rocky core whose mass is approximately equal to the mass of the Earth. Neptune's core is composed of silicate magnesium and iron.
Neptune's magnetic field is 27 times more powerful than Earth's.
Neptune's gravity is only 17% stronger than that of Earth.
Neptune is an icy planet made of ammonia, water and methane.
An interesting fact is that the planet itself rotates in the opposite direction from the rotation of the clouds.
A Great Dark Spot was discovered on the planet's surface in 1989.
SATELLITES OF NEPTUNE
Neptune has an officially registered number of 14 satellites. Neptune's moons are named after Greek gods and heroes: Proteus, Talas, Naiad, Galatea, Triton and others.
Neptune's largest satellite is Triton.
Triton moves around Neptune in a retrograde orbit. This means that its orbit around the planet is backwards compared to Neptune's other moons.
Most likely, Neptune once captured Triton - that is, the moon did not form on the spot, like the other moons of Neptune. Triton is locked in synchronous rotation with Neptune and is slowly spiraling towards the planet.
Triton, in about three and a half billion years, will be torn apart by its gravity, after which its debris will form another ring around the planet. This ring may be more powerful than the rings of Saturn.
Triton's mass is more than 99.5% of the total mass of all other Neptune satellites
Triton was most likely once a dwarf planet in the Kuiper Belt.
RINGS OF NEPTUNE
Neptune has six rings, but they are much smaller than Saturn's and are not easy to see.
Neptune's rings are made mostly of frozen water.
It is believed that the planet's rings are the remains of a once torn apart satellite.
VISITING NEPTUNE
In order for the ship to reach Neptune, it needs to travel a path that will take approximately 14 years.
The only spacecraft to visit Neptune is.
In 1989, Voyager 2 passed within 3,000 kilometers of Neptune's north pole. He circled the celestial body once.
During its flyby, Voyager 2 studied Neptune's atmosphere, its rings, magnetosphere and met Triton. Voyager 2 also took a look at Neptune's Great Dark Spot, a rotating storm system that has disappeared, according to Hubble Space Telescope observations.
Voyager 2's beautiful photographs of Neptune will long remain the only thing we have
Unfortunately, no one plans to explore the planet Neptune again in the coming years.
At the very outskirts of the solar system is the blue planet Neptune. Until recently, this planet had the eighth serial number in the planetary series, closing the group of gas giant planets. Today, when Pluto was reclassified as a dwarf planet, Neptune was the last known planet in the solar system. What is this distant world like? What is the last planet in the system of our star?
The Sun, located at a distance of 4.5 billion km from the planet, looks like a bright large star
The history of the discovery of the eighth planet
In 1846, a significant event occurred in the history of astronomy. For the first time, a large celestial object was discovered not as a result of visual observation of the celestial sphere. The planet was discovered through mathematical calculations, which made it possible to calculate the location of the object. Scientists were prompted to take such actions by the unusual behavior of Uranus, the seventh planet of the solar system. Back in 1781, astronomers, observing the third gas giant, discovered periodic fluctuations in the orbital path of Uranus, which indicated that the planet was affected by external gravitational forces. This fact gave reason to assume that there was some large celestial body beyond the orbit of Uranus.
Due to the close proximity of Uranus and Neptune (the distance between the objects is 10.876 AU), the planets closely interact with each other, influencing each other’s orbital parameters
However, the first assumptions remained only hypotheses for a long time, until in 1845-46 the English astronomer and mathematician John Couch Adams sat down to do mathematical calculations. Despite the fact that his scientific work, which proved the existence of another planet, did not cause a stir in the scientific community, Adams’ efforts were not in vain. Literally a year later, the Frenchman Laverrier, in a similar work, confirmed the correctness of Adams’ calculations, adding evidence in favor of the existence of a new planet. Only after two independent calculations were received did the scientific community begin to frantically search the night sky for a mysterious object in the area of the solar system determined by the calculations. The German Johann Halle managed to put an end to this issue, who on September 23, 1846 actually discovered a new planet on the outskirts of the solar system.
There were no particular difficulties with the name. The planetary disk had a distinct blue tint when observed through a telescope. This gave rise to the name given to the new planet in honor of Neptune, the ancient Roman god of the seas. Thus, after Jupiter, Saturn and Uranus, the firmament was replenished with another god. The credit for this goes to the director of the Pulkovo Observatory, Vasily Struve, who was the first to propose such a name.
Distance diagram: Neptune - Earth and Neptune - Sun. To denote such huge distances in astrophysics, it is customary to operate with astronomical units - A.E.
The discovered celestial body turned out to be quite large in size, which could really influence the position of Uranus in orbit. The newly discovered planet is located on the outskirts of the solar system, at a distance of 4.5 billion kilometers from the Sun. Our Earth is separated from the eighth planet by no less a distance - 4.3 billion kilometers.
Astrophysical parameters of the eighth planet
Being at such a great distance, Neptune is barely visible to optical instruments. This is explained by the fact that the planet barely crawls across the firmament and can easily be confused with a dimly twinkling star. The orbital path of the sea god takes 60 thousand years. In other words, when Neptune returns to the place where it was discovered in 1846, 60 thousand years will have passed on Earth.
Arrangement of the planets of the solar system in order. The four terrestrial planets are followed by four gas giant planets, the rank of which is completed by Neptune.
The astrophysical parameters of the orbit of the eighth planet were calculated at an early stage. Neptune has been found to have the following orbital characteristics:
- at perihelion the planet is at a distance of 4,452,940,833 km from the Sun;
- at aphelion, Neptune approaches the main body at a distance of 4,553,946,490 km;
- the orbital eccentricity is only 0.011214269;
- Neptune moves in orbit at a speed of 5.43 km/s;
- Neptunian days last 15 hours and 8 minutes;
- Neptune's axial tilt is 28.32°.
From the above data it is clear that the planet behaves quite impressively in space, except for the high speed with which Neptune rotates around its own axis. The angle of inclination of the object relative to the ecliptic plane allows the Sun to evenly illuminate the surface of this distant and cold world. This position of the object ensures the change of seasons, the duration of which is about 40 years.
As for the physical parameters, accurate data were obtained only at the end of the 20th century. Neptune turned out to be the fourth largest planet in the Solar System, behind its older brothers Jupiter, Saturn and Uranus. The diameter of this distant object is 49,244 km. It is characteristic that the discrepancies between the polar and equatorial compression of Neptune are insignificant. The planet is an almost perfect sphere, which is almost 4 times the size of our planet. Neptune's mass is 1.0243·10²⁶ kg. This is less than that of Jupiter and Saturn, but 17 times the mass of the Earth.
Comparison of the size of the planet Neptune with other planets of the solar system. Uranus and Neptune clearly stand out relative to the size of the gas giants Jupiter and Saturn.
Calculations obtained at a later time from the Voyager 2 space probe made it possible to obtain ideas about the density of the eighth planet, which is 1.638 g/cm³. This is three times less than the same parameter for the Earth. Because of this, the planet was classified as a gas giant planet. Despite this, scientists consider Neptune to be a transitional planet from terrestrial planets to planetary objects of gaseous and icy structure. Although it is 17 times more massive than Earth, Neptune is significantly inferior in mass to Jupiter - only 1/19 of the mass of the largest planet. The blue planet's gravity is second only to that of Jupiter.
Main characteristics of Neptune
After lengthy observations, it was revealed that Neptune does not have a solid surface. Like other giant planets, the eighth planet is characterized by the absence of a clear boundary between the atmosphere and the imaginary surface. Neptune's atmosphere is in constant motion, undergoing differential rotation. In the equatorial zone, the planet's rotation period is 5 hours longer than at the poles. Because of this difference in the atmosphere of the blue giant, a colossal air shift occurs, contributing to the emergence of strong winds. On the eighth planet, winds constantly blow, the speed of which is cosmic speed - 600 s. A sharp change in the direction of air flows causes storms, most of which are comparable in scale to the size of Jupiter's Red Spot.
A dark spot in Neptune's atmosphere. An object very much reminiscent in structure and dynamics of the Red Spot - the area of a colossal storm on Jupiter.
The chemical composition of the atmosphere of a distant planet resembles the structure of stellar matter. The air shell of Neptune is dominated by hydrogen, the amount of which varies between 50-80% depending on the height of the layers. The rest of the air surface layer is 19% helium, slightly less than 1.5% is methane. The blue color of the cosmic god is explained by the presence of methane in the atmosphere, which in the spectral range completely absorbs red waves. Unlike Uranus, which appears as a pale smudge in a telescope lens, Neptune has a deep blue color. This leads scientists to think about the presence in the planet’s atmosphere, in addition to methane, and other components that affect the color spectrum. These can be aerosols, presented in the form of ammonia crystals and water ice.
The exact depth of the atmospheric layer is still unknown. There is information about the presence of two layers - the troposphere and the stratosphere. Thanks to data obtained from Voyager 2, it was possible to calculate the atmospheric pressure at the tropopause, which is only 0.1 bar. As for the temperature balance, due to the enormous distance from the Sun, the kingdom of cold reigns on Neptune. Temperatures reach 200 °C with a minus sign. A mystery for scientists is the high temperature recorded in the thermosphere. In this area, a significant jump in temperature was noted, reaching values of 476 degrees Celsius with a plus sign.
Neptune's atmosphere is 80% hydrogen (H₂). Helium in the air envelope of the planet is 15%. In its chemical composition, the gas giant resembles a star in the initial stages of formation.
The presence of high temperatures in the planet’s thermosphere indicates the presence of ionization processes in Neptune’s atmosphere. According to another version, the gravitational forces of the planet itself interact with the atmosphere, generating kinetic energy in the process of friction.
As for the planet itself, it is possible that Neptune has a solid core. This is evidenced by the planet's strong magnetic field. Around the core is a thick layer of mantle, which is a hot and incandescent liquid substance. Presumably Neptunian mantle consists of ammonia, methane and water. The imaginary surface of the planet is hot ice. Due to the last factor, the planet is considered an ice giant, where most of the gases are frozen.
In its structure, Neptune is very similar to the structure of other gas giant planets, however, unlike Jupiter and Uranus, the gaseous components are represented by frozen ice
Latest research on Neptune and famous discoveries
The huge distance that separates our worlds does not allow intensive and detailed studies of Neptune. It takes four hours for sunlight to touch the surface of the eighth planet's atmosphere. To date, only one spacecraft launched from Earth has managed to reach the vicinity of Neptune. This happened in 1989, 12 years after the Voyager 2 space launch. With the discovery of Neptune, the size of the solar system almost doubled. Even at the time of the discovery of the planet, it was possible to discover its largest satellite, which received the gloomy name Triton. This satellite has a spherical planetary shape. Subsequently, it was possible to identify 12 more moons that have an irregular shape.
Neptune has 13 natural satellites. The largest of them are Triton, Nereid, Proteus and Thalassa.
After Voyager's flight, it became clear that Triton is the coldest place in the solar system. A temperature of -235⁰ C was recorded on the surface of the satellite.
Scientists assume that these objects were captured by a giant planet from the Kuiper belt. The nature of Neptune's rings is similar. To date, three main rings of the planet have been discovered: the Adams, Laverrier and Halle rings.
Subsequent studies of the most distant planet in the solar system were associated with the flight of the Neptune Orbiter. The launch was planned for 2016, but the launch of the probe had to be postponed. Presumably, work is now underway to expand the tasks for future research, which will include the operation of the probe in the outer regions of the Solar system.
Neptune is the eighth planet included in our solar system. Scientists discovered it first, based on constant observations of the sky and deep mathematical research. Urbain Joseph Le Verrier, after lengthy discussions, shared his observations with the Berlin Observatory, where they were studied by Johann Gottfried Halle. It was there that Neptune was discovered on September 23, 1846. Seventeen days later, his companion, Triton, was found.
The planet Neptune is located at a distance of 4.5 billion km from the Sun. It takes 165 years to complete its orbit. It cannot be seen with the naked eye, since it is located at a significant distance from the Earth.
The strongest winds reign in Neptune's atmosphere; according to some scientists, they can reach speeds of 2100 km/h. In 1989, during a flyby of Voyager 2, a Great Dark Spot was discovered in the southern hemisphere of the planet, exactly the same as the Great Red Spot on the planet Jupiter. In the upper atmosphere, Neptune's temperature is close to 220 degrees Celsius. The temperature at the center of Neptune ranges from 5400°K to 7000-7100°C, which corresponds to the temperature on the surface of the Sun and the internal temperature of most planets. Neptune has a fragmented and faint ring system that was discovered back in the 1960s but officially confirmed in 1989 by Voyager 2.
The history of the discovery of the planet Neptune
On December 28, 1612, Galileo Galilei explored Neptune, and then on January 29, 1613. But in both cases, he mistook Neptune for a fixed star that was conjunct Jupiter in the sky. That is why Galileo was not given credit for the discovery of Neptune.
In December 1612, during the first observation, Neptune was at a stationary point, and on the day of observation it began to move backward. Retrograde motion is observed when our planet overtakes the outer planet along its axis. Because Neptune was close to station, its motion was too weak for Galileo to see it with his small telescope.
Alexis Bouvard demonstrated astronomical tables of the orbit of the planet Uranus in 1821. Later observations showed strong deviations from the tables he created. Taking this circumstance into account, the scientist suggested that the unknown body with its gravity disturbs the orbit of Uranus. He sent his calculations to the royal astronomer Sir George Airy, who asked Kuh for clarification. He had already begun to draft an answer, but for some reason did not send it and did not insist on working on this issue.
In 1845-1846, Urbain Le Verrier, independently of Adams, quickly carried out his calculations, but his compatriots did not share his enthusiasm. After reviewing Le Verrier's first estimate of Neptune's longitude and its similarity with Adams' estimate, Airy managed to persuade James Chiles, director of the Cambridge Observatory, to begin a search that lasted from August to September. Chiles actually observed Neptune twice, but because he delayed processing the results until a later date, he was unable to identify the planet in a timely manner.
At this time, Le Verrier convinced the astronomer Johann Gottfried Halle, working at the Berlin Observatory, to start searching. Observatory student Heinrich d'Arre suggested to Halle that he compare a drawn map of the sky in the area of Le Verrier's predicted location with the view of the sky at the moment in order to observe the movement of the planet relative to the fixed stars. On the first night, the planet was discovered after approximately 1 hour of searching. Johann Encke, together with the director of the observatory, continued to observe the part of the sky where the planet was located for 2 nights, as a result of which they discovered its movement relative to the stars and were able to verify that it was in fact a new planet. On September 23, 1846, Neptune was discovered. It is within 1° of Le Verrier's coordinates and approximately 12° of the coordinates that were predicted by Adams.
Immediately after the discovery, a dispute ensued between the French and the British over the right to consider the discovery of the planet theirs. As a result, they came to a consensus and decided to consider Le Verrier and Adams as co-discoverers. In 1998, the “Neptune papers” were once again found, which were illegally appropriated by astronomer Olin J. Eggen and kept by him for thirty years. After his death they were found in his possession. Some historians, after reviewing the documents, believe that Adams does not deserve equal rights to discover the planet with Le Verrier. In principle, this has been questioned before, for example, since 1966 by Dennis Rawlins. In the magazine "Dio" he published an article demanding that Adams's equal right to discovery be recognized as theft. "Yes, Adams did some calculations, but he was somewhat unsure about where Neptune was located," Nicholas Collestrum said in 2003.
Origin of the name Neptune
For a certain time after its discovery, the planet Neptune was designated as "Le Verrier's planet" or as the "planet outer of Uranus." The idea of an official name was first put forward by Halle, who proposed the name “Janus”. Chiles in England suggested the name "Ocean".
Le Verrier, claiming that he had the right to name it, proposed to call it Neptune, mistakenly believing that this name was recognized by the French Bureau of Longitudes. The scientist tried to name the planet in October after his own name, Le Verrier, and was supported by the director of the observatory, but the initiative ran into resistance outside France. Almanacs quickly returned the name Herschel (after William Herschel, the discoverer) for Uranus and Le Verrier for the new planet.
But, despite this, Vasily Struve, director of the Pulkovo Observatory, will settle on the name “Neptune”. He announced his decision at the congress of the Imperial Academy of Sciences on December 29, 1846, which took place in St. Petersburg. This name gained support beyond the borders of Russia and very soon became the accepted international name for the planet.
physical characteristics
Neptune has a mass of 1.0243 × 1026 kg and acts as an intermediate link between the large gas giants and the Earth. Its weight is seventeen times that of Earth and 1/19 that of Jupiter. As for the equatorial radius of Neptune, it corresponds to 24,764 km, which is almost four times larger than the Earth’s. Uranus and Neptune are often classified as gas giants ("ice giants") due to their high concentrations of volatiles and smaller size.
Internal structure
It is immediately worth noting that the internal structure of the planet Neptune is similar to the structure of Uranus. The atmosphere makes up approximately 10-20% of the total mass of the planet, the distance from the surface to the atmosphere is 10-20% of the distance from the planet's surface to the core. The pressure near the core can be 10 GPa. Concentrations of ammonia, methane and water have been found in the lower atmosphere.
This hotter and darker region gradually condenses into a superheated liquid mantle, the temperature of which reaches 2000 - 5000 K. The weight of the planet's mantle is ten to fifteen times that of Earth, according to various estimates, and it is rich in ammonia, water, methane and other compounds. This matter, according to generally accepted terminology, is called icy, even though it is a dense and very hot liquid. This liquid, which has high electrical conductivity, is often called an ocean of aqueous ammonia. Methane at a depth of 7 thousand km decomposes into diamond crystals that “fall” onto the core. Scientists have hypothesized that there is an entire ocean of “diamond liquid.” The planet's core is made of nickel, iron and silicates and weighs 1.2 times our planet. In the center the pressure reaches 7 megabars, which is millions of times higher than on Earth. In the center the temperature reaches 5400 K.
Atmosphere of Neptune
Scientists have discovered helium and waterfall in the upper atmosphere. At this height they are 19% and 80%. In addition, traces of methane can be traced. Methane absorption bands can be traced at wavelengths exceeding 600 nm in the infrared and red parts of the spectrum. As with Uranus, methane's absorption of red light is a key factor in giving Neptune its blue hue, although the bright azure is different from the moderate aquamarine color of Uranus. Since the percentage of methane in the atmosphere is not much different from that of Uranus, scientists speculate that there is some unknown atmospheric component that contributes to the formation of the blue color. The atmosphere is divided into two main regions, namely the lower troposphere, in which there is a decrease in temperature with height, and the stratosphere, where another pattern can be observed - temperature increases with height. The tropopause boundary (located between them) is located at a pressure level of 0.1 bar. At pressure levels below 10-4 - 10-5 microbars, the stratosphere gives way to the thermosphere. Gradually the thermosphere turns into the exosphere. Models of the troposphere suggest that, given altitude, it consists of clouds of approximate compositions. In the pressure zone below 1 bar there are upper-level clouds, where the temperature is conducive to methane condensation.
Clouds of hydrogen sulfide and ammonia form at pressures between 1 and 5 bar. At higher pressures, clouds may consist of ammonium sulfide, ammonia, water and hydrogen sulfide. Deeper down, at a pressure of about 50 bar, clouds of water ice can form in the case of temperatures of 0 °C. Scientists suggest that this zone may contain clouds of hydrogen sulfide and ammonia. In addition, it is possible that clouds of hydrogen sulfide and ammonia may be found in this area.
For such a low temperature, Neptune is too far from the Sun for it to heat the thermosphere with UV radiation. It is possible that this phenomenon is a consequence of atmospheric interaction with ions located in the planet’s magnetic field. Another theory says that the main heating mechanism is gravity waves from the inner regions of Neptune, which subsequently dissipate in the atmosphere. The thermosphere contains traces of carbon monoxide and water brought in from external sources (dust and meteorites).
Neptune Climate
It is from the differences between Uranus and Neptune - the level of meteorological activity. Voyager 2, which flew near uranium in 1986, recorded weak atmospheric activity. Neptune, in contrast to Uranus, exhibited clear weather changes during the 1989 survey.
The planet's weather is characterized by a serious dynamic system of storms. Moreover, the wind speed can sometimes reach about 600 m/s (supersonic speed). While tracking the movement of clouds, a change in wind speed was noticed. Eastward from 20 m/s; in the west - to 325 m/s. As for the upper cloud layer, the wind speed here also varies: along the equator from 400 m/s; at the poles – up to 250 m/s. Moreover, most winds give a direction that is opposite to the rotation of Neptune around its axis. The pattern of winds shows that their direction at high latitudes coincides with the direction of rotation of the planet, and at low latitudes it is completely opposite to it. The difference in the direction of the winds, as scientists believe, is a consequence of the “screen effect” and is not associated with deep atmospheric processes. The content of ethane, methane and acetylene in the atmosphere in the equator region is tens or even hundreds of times higher than the content of these substances in the pole region. This observation gives reason to believe that upwelling exists at Neptune’s equator and closer to the poles. In 2007, scientists noticed that the upper troposphere of the planet's south pole was 10 °C warmer compared to the other part of Neptune, where the average temperature is −200 °C. Moreover, such a difference is quite enough for methane in other areas of the upper atmosphere to be frozen and gradually seep into space at the south pole.
Due to seasonal changes, cloud bands in the planet's southern hemisphere increased in albedo and size. This trend was observed back in 1980; according to experts, it will last until 2020 with the onset of a new season on the planet, which changes every forty years.
Moons of Neptune
Currently, Neptune has thirteen known moons. The largest of them weighs more than 99.5% of the total mass of all the planet’s satellites. This is Triton, which was discovered by William Lassell seventeen days after the discovery of the planet itself. Triton, unlike other large moons in our solar system, has a retrograde orbit. It is possible that it was captured by Neptune's gravity, and may have been a dwarf planet in the past. It is at a small distance from Neptune to be locked in synchronous rotation. Triton, due to tidal acceleration, is slowly moving in a spiral towards the planet and as a result, when it reaches the Roche limit, it will be destroyed. As a result, a ring will be formed that will be more powerful than the rings of Saturn. This is expected to happen within 10 to 100 million years.
Triton is one of 3 moons that have an atmosphere (along with Titan and Io). The possibility of the existence of a liquid ocean under the icy crust of Triton, similar to the ocean of Europa, is indicated.
The next discovered satellite of Neptune was Nereid. It has an irregular shape and is among the highest orbital eccentricities.
Between July and September 1989, six more new satellites were discovered. Among them, it is worth noting Proteus, which has an irregular shape and high density.
The four inner satellites are Thalassa, Naiad, Galatea and Despina. Their orbits are so close to the planet that they are within its rings. Larissa, next in line, was first opened in 1981.
Between 2002 and 2003, five more irregularly shaped moons of Neptune were discovered. Since Neptune was considered the Roman god of the sea, his moons were named after other sea creatures.
Observing Neptune
It's no secret that Neptune is not visible from Earth with the naked eye. The dwarf planet Ceres, the Galilean moons of Jupiter and asteroids 2 Pallas, 4 Vesta, 3 Juno, 7 Iris and 6 Hebe are visible brighter in the sky. To observe the planet, you need a telescope with a magnification of 200x and a diameter of at least 200-250 mm. In this case, you can see the planet as a small bluish disk, reminiscent of Uranus.
Every 367 days, for an earthly observer, the planet Neptune enters into an apparent retrograde motion, forming certain imaginary loops against the background of other stars during each opposition.
Observing the planet at radio waves shows that Neptune is the source of irregular flares and continuous emission. Both phenomena are explained by a rotating magnetic field. Neptune's storms are clearly visible in the infrared part of the spectrum. You can determine their size and shape, and accurately track their movement.
In 2016, NASA plans to launch the Neptune Orbiter spacecraft to Neptune. To date, no exact launch dates have been officially announced; the plan for exploring the Solar System does not include this device.
At the very outskirts of the solar system is the blue planet Neptune. Until recently, this planet had the eighth serial number in the planetary series, closing the group of gas giant planets. Today, when Pluto was reclassified as a dwarf planet, Neptune was the last known planet in the solar system. What is this distant world like? What is the last planet in the system of our star?
The Sun, located at a distance of 4.5 billion km from the planet, looks like a bright large star
The history of the discovery of the eighth planet
In 1846, a significant event occurred in the history of astronomy. For the first time, a large celestial object was discovered not as a result of visual observation of the celestial sphere. The planet was discovered through mathematical calculations, which made it possible to calculate the location of the object. Scientists were prompted to take such actions by the unusual behavior of Uranus, the seventh planet of the solar system. Back in 1781, astronomers, observing the third gas giant, discovered periodic fluctuations in the orbital path of Uranus, which indicated that the planet was affected by external gravitational forces. This fact gave reason to assume that there was some large celestial body beyond the orbit of Uranus.
Due to the close proximity of Uranus and Neptune (the distance between the objects is 10.876 AU), the planets closely interact with each other, influencing each other’s orbital parameters
However, the first assumptions remained only hypotheses for a long time, until in 1845-46 the English astronomer and mathematician John Couch Adams sat down to do mathematical calculations. Despite the fact that his scientific work, which proved the existence of another planet, did not cause a stir in the scientific community, Adams’ efforts were not in vain. Literally a year later, the Frenchman Laverrier, in a similar work, confirmed the correctness of Adams’ calculations, adding evidence in favor of the existence of a new planet. Only after two independent calculations were received did the scientific community begin to frantically search the night sky for a mysterious object in the area of the solar system determined by the calculations. The German Johann Halle managed to put an end to this issue, who on September 23, 1846 actually discovered a new planet on the outskirts of the solar system.
There were no particular difficulties with the name. The planetary disk had a distinct blue tint when observed through a telescope. This gave rise to the name given to the new planet in honor of Neptune, the ancient Roman god of the seas. Thus, after Jupiter, Saturn and Uranus, the firmament was replenished with another god. The credit for this goes to the director of the Pulkovo Observatory, Vasily Struve, who was the first to propose such a name.
Distance diagram: Neptune - Earth and Neptune - Sun. To denote such huge distances in astrophysics, it is customary to operate with astronomical units - A.E.
The discovered celestial body turned out to be quite large in size, which could really influence the position of Uranus in orbit. The newly discovered planet is located on the outskirts of the solar system, at a distance of 4.5 billion kilometers from the Sun. Our Earth is separated from the eighth planet by no less a distance - 4.3 billion kilometers.
Astrophysical parameters of the eighth planet
Being at such a great distance, Neptune is barely visible to optical instruments. This is explained by the fact that the planet barely crawls across the firmament and can easily be confused with a dimly twinkling star. The orbital path of the sea god takes 60 thousand years. In other words, when Neptune returns to the place where it was discovered in 1846, 60 thousand years will have passed on Earth.
Arrangement of the planets of the solar system in order. The four terrestrial planets are followed by four gas giant planets, the rank of which is completed by Neptune.
The astrophysical parameters of the orbit of the eighth planet were calculated at an early stage. Neptune has been found to have the following orbital characteristics:
- at perihelion the planet is at a distance of 4,452,940,833 km from the Sun;
- at aphelion, Neptune approaches the main body at a distance of 4,553,946,490 km;
- the orbital eccentricity is only 0.011214269;
- Neptune moves in orbit at a speed of 5.43 km/s;
- Neptunian days last 15 hours and 8 minutes;
- Neptune's axial tilt is 28.32°.
From the above data it is clear that the planet behaves quite impressively in space, except for the high speed with which Neptune rotates around its own axis. The angle of inclination of the object relative to the ecliptic plane allows the Sun to evenly illuminate the surface of this distant and cold world. This position of the object ensures the change of seasons, the duration of which is about 40 years.
As for the physical parameters, accurate data were obtained only at the end of the 20th century. Neptune turned out to be the fourth largest planet in the Solar System, behind its older brothers Jupiter, Saturn and Uranus. The diameter of this distant object is 49,244 km. It is characteristic that the discrepancies between the polar and equatorial compression of Neptune are insignificant. The planet is an almost perfect sphere, which is almost 4 times the size of our planet. Neptune's mass is 1.0243·10²⁶ kg. This is less than that of Jupiter and Saturn, but 17 times the mass of the Earth.
Comparison of the size of the planet Neptune with other planets of the solar system. Uranus and Neptune clearly stand out relative to the size of the gas giants Jupiter and Saturn.
Calculations obtained at a later time from the Voyager 2 space probe made it possible to obtain ideas about the density of the eighth planet, which is 1.638 g/cm³. This is three times less than the same parameter for the Earth. Because of this, the planet was classified as a gas giant planet. Despite this, scientists consider Neptune to be a transitional planet from terrestrial planets to planetary objects of gaseous and icy structure. Although it is 17 times more massive than Earth, Neptune is significantly inferior in mass to Jupiter - only 1/19 of the mass of the largest planet. The blue planet's gravity is second only to that of Jupiter.
Main characteristics of Neptune
After lengthy observations, it was revealed that Neptune does not have a solid surface. Like other giant planets, the eighth planet is characterized by the absence of a clear boundary between the atmosphere and the imaginary surface. Neptune's atmosphere is in constant motion, undergoing differential rotation. In the equatorial zone, the planet's rotation period is 5 hours longer than at the poles. Because of this difference in the atmosphere of the blue giant, a colossal air shift occurs, contributing to the emergence of strong winds. On the eighth planet, winds constantly blow, the speed of which is cosmic speed - 600 s. A sharp change in the direction of air flows causes storms, most of which are comparable in scale to the size of Jupiter's Red Spot.
A dark spot in Neptune's atmosphere. An object very much reminiscent in structure and dynamics of the Red Spot - the area of a colossal storm on Jupiter.
The chemical composition of the atmosphere of a distant planet resembles the structure of stellar matter. The air shell of Neptune is dominated by hydrogen, the amount of which varies between 50-80% depending on the height of the layers. The rest of the air surface layer is 19% helium, slightly less than 1.5% is methane. The blue color of the cosmic god is explained by the presence of methane in the atmosphere, which in the spectral range completely absorbs red waves. Unlike Uranus, which appears as a pale smudge in a telescope lens, Neptune has a deep blue color. This leads scientists to think about the presence in the planet’s atmosphere, in addition to methane, and other components that affect the color spectrum. These can be aerosols, presented in the form of ammonia crystals and water ice.
The exact depth of the atmospheric layer is still unknown. There is information about the presence of two layers - the troposphere and the stratosphere. Thanks to data obtained from Voyager 2, it was possible to calculate the atmospheric pressure at the tropopause, which is only 0.1 bar. As for the temperature balance, due to the enormous distance from the Sun, the kingdom of cold reigns on Neptune. Temperatures reach 200 °C with a minus sign. A mystery for scientists is the high temperature recorded in the thermosphere. In this area, a significant jump in temperature was noted, reaching values of 476 degrees Celsius with a plus sign.
Neptune's atmosphere is 80% hydrogen (H₂). Helium in the air envelope of the planet is 15%. In its chemical composition, the gas giant resembles a star in the initial stages of formation.
The presence of high temperatures in the planet’s thermosphere indicates the presence of ionization processes in Neptune’s atmosphere. According to another version, the gravitational forces of the planet itself interact with the atmosphere, generating kinetic energy in the process of friction.
As for the planet itself, it is possible that Neptune has a solid core. This is evidenced by the planet's strong magnetic field. Around the core is a thick layer of mantle, which is a hot and incandescent liquid substance. Presumably Neptunian mantle consists of ammonia, methane and water. The imaginary surface of the planet is hot ice. Due to the last factor, the planet is considered an ice giant, where most of the gases are frozen.
In its structure, Neptune is very similar to the structure of other gas giant planets, however, unlike Jupiter and Uranus, the gaseous components are represented by frozen ice
Latest research on Neptune and famous discoveries
The huge distance that separates our worlds does not allow intensive and detailed studies of Neptune. It takes four hours for sunlight to touch the surface of the eighth planet's atmosphere. To date, only one spacecraft launched from Earth has managed to reach the vicinity of Neptune. This happened in 1989, 12 years after the Voyager 2 space launch. With the discovery of Neptune, the size of the solar system almost doubled. Even at the time of the discovery of the planet, it was possible to discover its largest satellite, which received the gloomy name Triton. This satellite has a spherical planetary shape. Subsequently, it was possible to identify 12 more moons that have an irregular shape.
Neptune has 13 natural satellites. The largest of them are Triton, Nereid, Proteus and Thalassa.
After Voyager's flight, it became clear that Triton is the coldest place in the solar system. A temperature of -235⁰ C was recorded on the surface of the satellite.
Scientists assume that these objects were captured by a giant planet from the Kuiper belt. The nature of Neptune's rings is similar. To date, three main rings of the planet have been discovered: the Adams, Laverrier and Halle rings.
Subsequent studies of the most distant planet in the solar system were associated with the flight of the Neptune Orbiter. The launch was planned for 2016, but the launch of the probe had to be postponed. Presumably, work is now underway to expand the tasks for future research, which will include the operation of the probe in the outer regions of the Solar system.
