The Mystery of Planet 8

Posted: January 29, 2012 by tallbloke in Astronomy, Astrophysics, atmosphere, solar system dynamics, weather


Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. 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.[12] On average, Neptune orbits the Sun at a distance of 30.1 AU, approximately 30 times the Earth–Sun distance.


Neptune’s more varied weather when compared to Uranus is believed to be due in part to its higher internal heat.[83] Although Neptune lies half again as far from the Sun as Uranus, and receives only 40% its amount of sunlight,[13] the two planets’ surface temperatures are roughly equal.[83] The upper regions of Neptune’s troposphere reach a low temperature of −221.4 °C (51.8 K). At a depth where the atmospheric pressure equals 1 bar (100 kPa), the temperature is −201.15 °C (72.00 K).[84] Deeper inside the layers of gas, the temperature rises steadily. As with Uranus, the source of this heating is unknown, but the discrepancy is larger: Uranus only radiates 1.1 times as much energy as it receives from the Sun;[85] while Neptune radiates about 2.61 times as much energy as it receives from the Sun.[86] Neptune is the farthest planet from the Sun, yet its internal energy is sufficient to drive the fastest planetary winds seen in the Solar System. Several possible explanations have been suggested, including radiogenic heating from the planet’s core,[87] conversion of methane under high pressure into hydrogen, diamond and longer hydrocarbons (the hydrogen and diamond would then rise and sink, respectively, releasing gravitational potential energy),[87][88] and convection in the lower atmosphere that causes gravity waves to break above the tropopause.[89][90]

At high altitudes, Neptune’s atmosphere is 80% hydrogen and 19% helium.[17] A trace amount of methane is also present. Prominent absorption bands of methane occur at wavelengths above 600 nm, in the red and infrared portion of the spectrum. As with Uranus, this absorption of red light by the atmospheric methane is part of what gives Neptune its blue hue,[49] although Neptune’s vivid azure differs from Uranus’s milder cyan. Since Neptune’s atmospheric methane content is similar to that of Uranus, some unknown atmospheric constituent is thought to contribute to Neptune’s colour.[15]

Neptune’s atmosphere is sub-divided into two main regions; the lower troposphere, where temperature decreases with altitude, and the stratosphere, where temperature increases with altitude. The boundary between the two, the tropopause, occurs at a pressure of 0.1 bars (10 kPa).[13] The stratosphere then gives way to the thermosphere at a pressure lower than 10−5 to 10−4 microbars (1 to 10 Pa).[13] The thermosphere gradually transitions to the exosphere.

In contrast to the relatively featureless atmosphere of Uranus, Neptune’s atmosphere is notable for its active and visible weather patterns. For example, at the time of the 1989 Voyager 2 flyby, the planet’s southern hemisphere possessed a Great Dark Spot comparable to the Great Red Spot on Jupiter. These weather patterns are driven by the strongest sustained winds of any planet in the Solar System, with recorded wind speeds as high as 2,100 km/h.[16] Because of its great distance from the Sun, Neptune’s outer atmosphere is one of the coldest places in the Solar System, with temperatures at its cloud tops approaching −218 °C (55 K). Temperatures at the planet’s centre are approximately 5,400 K (5,000 °C).[17][18]

For reasons that remain obscure, the planet’s thermosphere is at an anomalously high temperature of about 750 K.[53][54] The planet is too far from the Sun for this heat to be generated by ultraviolet radiation. One candidate for a heating mechanism is atmospheric interaction with ions in the planet’s magnetic field. Other candidates are gravity waves from the interior that dissipate in the atmosphere. The thermosphere contains traces of carbon dioxide and water, which may have been deposited from external sources such as meteorites and dust.[50][52]

Wikipedia is still pretty good for some stuff we’ll be needing.

  1. Anybody computed the expected GH effect of all that methane?

  2. adolfogiurfa says:

    So-called thermal anomalies have been seen on Saturn, Jupiter, Io, Enceladus, as well as on comets and moons. The various effects on comets, for instance, have been shown to be caused by plasma discharge.

    Massive electrical disturbances deep below the clouds on Neptune will generate radio noise, as well as eruptions of gases from its lower atmosphere into the stratosphere where they form visible features. Those massive lightning discharges form electrical conduits that connect through Neptune’s ionosphere and magnetosphere with the Sun’s electrical environment. Thermal imaging equipment sees the warm upwelling atmosphere and interprets it merely as thermal convection.

    The Electric Universe model of Neptune postulates that hot spots, hot poles, hypersonic winds (wind speeds on Neptune are estimated to be around 2000 kilometers per hour), and atmospheric banding indicate that Neptune is an electrically active planet connected to the Sun’s electric circuit.

  3. allan says:

    -Neptune’s Herald
    Apr 09, 2010
    Summer has finally come to Triton.

    Neptune’s largest moon accompanies the giant gas planet as it travels in an elliptical orbit around the Sun at an average distance of about 4,495,060,000 kilometers. Neptune requires approximately 165 Earth years to complete one revolution, so summer arrives at infrequent intervals on its near planet-sized moon.

    On August 25, 1989, Voyager 2 became the first spacecraft to return close-up images of Neptune and its moons. Neptune is now officially recognized as the most distant planet from the Sun, since Pluto was voted to be a Kuiper Belt Object. It was during Voyager’s flyby that six of Neptune’s thirteen known moons were discovered.

    Triton is in a retrograde orbit around Neptune, circling the planet opposite to the direction of its rotation, and is the only moon in the Solar System to exhibit that configuration. Most of its other moons are not visible from Earth, and little is known about them. About half are so close to Neptune that Earth-based telescopes are not able to resolve them against its background.

    Triton is one of the Solar System’s strangest moons. First, it has an atmosphere, cold and thin as it is. However, it shares that characteristic with only two others: Jupiter’s moon Io, and Saturn’s moon Titan. Triton’s atmospheric pressure is greater than Io’s but less than Titan’s: only 1/100,000 that of Earth.

    Second, its anomalous retrograde orbit could indicate that Triton is a captured body, but one that is unusually big. Triton is two-thirds the size of Earth’s Moon. Third, its temperature makes it the coldest place known in the Solar System at -235 Celsius, yet so-called “nitrogen geysers” were seen spewing out of cracks in its surface. It is thought that those gas eruptions are what give Triton its atmosphere.

    The geyser-like formations shooting nitrogen gas and dust particles eight kilometers into space were one of the Voyager mission’s greatest surprises. They were called “ice volcanoes,” and several were identified in the south polar region.

    Triton’s surface features resemble those on Ariel, one of the moons circling Uranus; or those seen on Enceladus, one of Saturn’s moons; as well as Jupiter’s moons Europa, Ganymede, and Io. There are also polar ice caps similar to those on Mars, although Triton appears to most resemble Pluto in temperature, size, and chemical composition.

    According to a recent press release, the European Southern Observatory (ESO) has used their Very large Telescope to perform an infrared analysis of Triton’s atmosphere. Since Triton changes seasons once every forty years, this is the first time in over a century that summertime observations have even been possible.

    The southern summer solstice began in 2000, and scientists think that the atmosphere has become much thicker since then due to the sublimation of ices off the moon’s surface. Not just nitrogen, but carbon monoxide and methane have been detected in an upper layers of ice. They believe it is vapors from those thin layers, evaporated by the remote Sun, that have thickened the atmosphere.

    The geysers, darkened cavities, and “wind streaks” on Triton have been explained as electric discharge effects in other locations. A previous Thunderbolts Picture of the Day noted an association with the bizarre “Dalmatian spots” and geysers on Mars. The apparent role of charged particle beams excavating ice, and provoking massive geyser activity was offered as a possible explanation:

    “If the dark spotting on Mars’ south polar ice is indeed caused by charged particle streams, one of the first things we should look for is an active response of the surface to these events. Since the dark spotting is occurring in the Martian south polar spring, that would be the time to look for signs of energetic activity, not unlike the so-called ‘volcanic’ plumes of Jupiter’s closest moon Io, or the ‘geysers’ of Saturn’s moon Enceladus.”

    Consensus scientists typically ignore electricity when observing events in Neptune’s frigid vicinity. They do not consider that similar formations on Io, Enceladus, or Mars are even relevant to the geological condition of Triton. They do not realize that those differences are not an issue when an electrical interpretation is considered.

    Instead of the Sun’s heat influencing the change of seasons on Triton, perhaps the orientation of the moon within the electric fields generated by its parent body should be considered.

    Stephen Smith

  4. tchannon says:

    Fun stuff about Neptune but too little is actually known, as well as too far from the sun to be of much interest.

    Rog will like this but is old.

    Lot of info in this paper

  5. wayne says:

    With a TSI of just 1.5 W/m2, whatever energy that is driving the lapse and the winds doesn’t come from radiation or GH gases, that’s for sure! That also means the 2.6 time being emitted is just 2.4 W/m2 more. I mean, we are not even talking about a flashlight worth of light, more like an LED per square meter.

  6. tallbloke says:

    too far from the sun to be of much interest.

    I beg to differ Tim. Neptune’s mysterious ability to put out more energy than it receives from the Sun from such a small core is of supreme interest in my view. OK, it’s not much in absolute terms, but what accounts for it? Wiki offers a few ideas, but there are more. Some moons which have liquid water under ice crusts are thought to be warmed by ‘gravitational squeezing’ which arises because of the harmonics involved in their orbits. Is there something similar happening to Neptune?

    Has anyone applied the maths to see how the temperature at standard pressure compares with the Nikolov-Zeller theory or the Huffman hypothesis? Ned? Harry? Weigh in please.

  7. Tenuc says:

    tallbloke says:
    January 30, 2012 at 9:44 am
    “Has anyone applied the maths to see how the temperature at standard pressure compares with the Nikolov-Zeller theory or the Huffman hypothesis?…”

    Not so sure we have good enough temperature or pressure estimates for Neptune to prove anything. After all, we seem to be having enough trouble getting accurate data to produce these metrics even for our atmosphere… 🙂

  8. tallbloke says:

    From the text above:
    “The upper regions of Neptune’s troposphere reach a low temperature of −221.4 °C (51.8 K). At a depth where the atmospheric pressure equals 1 bar (100 kPa), the temperature is −201.15 °C (72.00 K)”


    Neptune’s atmosphere is sub-divided into two main regions; the lower troposphere, where temperature decreases with altitude, and the stratosphere, where temperature increases with altitude. The boundary between the two, the tropopause, occurs at a pressure of 0.1 bars (10 kPa)

    So once again, we have the tropopause at around the 0.1bar level. Can’t we make a stab at comparing Neptune with Earth and Venus with these figures via N&Z’s equations? Given that Neptune radiates more than it receives, it probably won’t lie on their curve, but it would be interesting to know where it does sit in relation to it I think.

  9. Anything is possible says:

    “Internal structure
    Neptune’s internal structure resembles that of Uranus. Its atmosphere forms about 5 to 10 percent of its mass and extends perhaps 10 to 20 percent of the way towards the core, where it reaches pressures of about 10 GPa. Increasing concentrations of methane, ammonia and water are found in the lower regions of the atmosphere.[17]

    The internal structure of Neptune:
    1. Upper atmosphere, top clouds
    2. Atmosphere consisting of hydrogen, helium and methane gas
    3. Mantle consisting of water, ammonia and methane ices
    4. Core consisting of rock (silicates and nickel-iron)
    The mantle reaches temperatures of 2,000 K to 5,000 K. It is equivalent to 10 to 15 Earth masses and is rich in water, ammonia and methane.[1] As is customary in planetary science, this mixture is referred to as icy even though it is a hot, highly dense fluid. This fluid, which has a high electrical conductivity, is sometimes called a water-ammonia ocean.[45] At a depth of 7000 km, the conditions may be such that methane decomposes into diamond crystals that then precipitate toward the core.[46] The mantle may consist of a layer of ionic water where the water molecules break down into a soup of hydrogen and oxygen ions, and deeper down superionic water in which the oxygen crystallises but the hydrogen ions float around freely within the oxygen lattice.[47]
    The core of Neptune is composed of iron, nickel and silicates, with an interior model giving a mass about 1.2 times that of the Earth.[48] The pressure at the centre is 7 Mbar (700 GPa), millions of times more than that on the surface of the Earth, and the temperature may be 5,400 K.[17][18]”

    For the purposes of evaluating N + Z should be mantle be considered as a continuation of the atmosphere, an ocean, a continuation of the planet’s rocky surface or something entirely separate?

    Assuming it to be “atmosphere” plugging in a value of 5400K for the planet’s surface temperature gives an NTE of 191.49!!, but given a surface pressure of 700GPa, that may not be as insane as it first looks…….

  10. tallbloke says:

    AiP: Good question. Maybe something could be gained by approaching the problem the other way. Work out what notional surface temperature would lie on the N&Z curve and see what depth that equates to in the Neptunian atmosphere/icy fluid. That might tell us something.

  11. Brian H says:

    That core temp is about the same as the surface of the Sun.

  12. Anything is possible says:

    Internal structure of Jupiter….

    “This picture illustrates the internal structure of Jupiter. The outer layer is primarily composed of molecular hydrogen. At greater depths the hydrogen starts resembling a liquid. At 10,000 kilometers below Jupiter’s cloud top liquid hydrogen reaches a pressure of 1,000,000 bar with a temperature of 6,000 K. At this state hydrogen changes into a phase of liquid metallic hydrogen. In this state, the hydrogen atoms break down yielding ionized protons and electrons similar to the Sun’s interior. Below this is a layer dominated by ice where “ice” denotes a soupy liquid mixture of water, methane, and ammonia under high temperatures and pressures. Finally at the center is a rocky or rocky-ice core of up to 10 Earth masses.1 The central pressure of Jupiter is 80 Million Bars, and the temperature is 25,000 K.”

    Sounding familiar?

  13. Anything is possible says:

    The internal structure of all 4 gas giants appear to be very similar, with a small rocky core surrounded by incredibly thick “atmospheres” where pressures are so great that the heavier gases (water, ammonia, methane) separate out from the lighter ones (hydrogen, helium) and become liquidised.

    At the bottom of the “atmospheres”, where they meet the rocky core, the extreme pressures generate temperatures of ‘000’s K.

    I hereby propose that the title of this thread be changed to “The mystery of planets 5,6,7 & 8”

  14. tallbloke says:

    Brian: and like the Sun, Neptune exhibits an ‘anomalously high corona temperature. At the other end of the solar system. Hmmm.

    AiP: Yebbut, that’d spoil the fun wouldn’t it? 🙂

  15. Keep in mind, the internal structures look the same now because they all come from the same theory…nobody’s cut a slice off Jupiter to find out.

    The one atmospheric probe (Galileo’s) ended up measuring the unexpected. So there’s only so much we can infer from the gas giants.

  16. wayne says:

    @ Anything is possible:
    January 30, 2012 at 8:17 pm

    New thought after reading your comment on the gas giants (Jupiter). Now run Dr. Brown’s thermodynamic logic in reverse… if such planets should really be isothermal with no pressure lapse, why would they not? Hmm.. have to think a bit on that… I still have a feeling he is wrong on gravity… though I also wild guessed isothermal just after Christmas when this whole topic became an issue. One way surfaces would be cooler than the other. Think suns.

    Maybe the only way is to answer this is to send up the space cowboys to drill to the center of an incoming ice comet and see if they hit ‘water’. 😉

  17. kuhnkat says:


    hyperspace or Birkeland Currents?? 8>)

  18. P.G. Sharrow says:

    @Lucy Skywalker says:
    January 30, 2012 at 10:36 pm

    This one fascinates me

    Mauna Loa, who’d a thunk it?

    Lucy! you have just “discovered” the planetary belly button!! 😎 pg

  19. tchannon says:

    Expect if anything this is golden section stuff.

  20. tchannon says:

    I’ll stick a radioactive link found on Bishop Hill in here.

    Earth getting heavier because of GW

  21. tallbloke says:

    From Wikipedia:
    Neptune also resembles Uranus in its magnetosphere, with a magnetic field strongly tilted relative to its rotational axis at 47° and offset at least 0.55 radii, or about 13500 km from the planet’s physical centre. Before Voyager 2’s arrival at Neptune, it was hypothesised that Uranus’s tilted magnetosphere was the result of its sideways rotation. In comparing the magnetic fields of the two planets, scientists now think the extreme orientation may be characteristic of flows in the planets’ interiors. This field may be generated by convective fluid motions in a thin spherical shell of electrically conducting liquids (probably a combination of ammonia, methane and water)[50] resulting in a dynamo action.[55]

    Lots of unsaid stuff here but if the Neptunian ‘dynamo’ is centred on one side of it’s atmosphere rather than in the core, this means that the determination of the rotation rate of the core of Jupiter from the radio waves emanating from its magnetosphere is likely wrong.

    I’m interested in this because I think there is a possible link between rotation rates, atmospheric angular momentum, atmospheric composition and surface temperature. Newton got around the problem of the momenta of planets by calling them their ‘innate motion’. This is plainly a cop-out. How do planets convert energy to maintain their orbits and rates of axial rotation? The planets with strong magnetospheres spin quickly, or at least their atmospheres do. Venus’ core spins slowly, and it has no magnetosphere of its own. there is small one induced by the heliomagnetic field though.

    It’s a good puzzle.

  22. P.G. Sharrow says:

    I wonder where the “belly button” is relative to the magnetic poles? Actually the “south” magnetic pole to be more exact. pg

  23. Anything is possible says:

    Hey, everyone check this out :

    Compare the average surface temperatures given in the text :

    “The mean surface temperature of Mercury is 442.5 K,[3] but it ranges from 100 K to 700 K”

    with those given in the table )top RHS) :

    Surface temp. min mean max
    0°N, 0°W 100K 340K 700K
    85°N, 0°W 80K 200K 380K

    Explanations, anyone?

  24. Anything is possible says:

    The mystery of planet 1 (:-

  25. tallbloke says:

    Thanks Ulric, very interesting article. I wonder if the anomalously high temperature of the Neptunian corona is linked to it’s strangely off-centre magnetosphere providing the dynamics which maximise Joule Heating.

  26. tallbloke says:

    AiP, Mercury is so close to the Sun the solar disc is subtending plenty of heat onto its poles.

  27. Anything is possible says:

    Thanks TB, but that wasn’t actually the mystery I was referring to….

    How the heck can Mercury have a “mean surface temperature of 442.5K” (a figure that has achieved wide, unthinking acceptance), when the mean temperature is 340K at the equator, and 200K at the poles?

    Clearly, it can’t. Either the figures in the table are incorrect, or the figure in the text is.

    If it is the latter, that represents further empirical evidence that N & Z’s application of the SB-law is far more accurate than the traditional one adopted by greenhouse theorists……

  28. tallbloke says:

    Heh. Sorry AiP, I completely missed your point. Yes indeed! Very odd. An error in Wikipedia. Who’d have thought that was possible. 😉

  29. tallbloke says:

    AiP, I’ve left a note on the discussion page. When they alter the values, we’ll go back and tell them they are wrong. 🙂

  30. Anything is possible says:

    Nice one, TB. It will be interesting to see how (if) they respond.

  31. tallbloke says:

    AiP: A response plus my additional info. 😉

    The info panel on the right of the page says the average surface temperature varies from 340K at the equator to 200K at the poles, but the main text says the overall average surface temperature is 442.5K. This is not physically possible. — Preceding unsigned comment added by ME! 🙂 (talk) 21:49, 6 February 2012 (UTC)

    Yes, I have no idea where the temperatures in the infobox come from. They need better referencing. Regards, RJH (talk) 22:21, 6 February 2012 (UTC)

    Thanks. It may be that the info panel is correct and NASA’s figure is wrong. Stefan-Boltzmann has been badly misapplied to hemispheres. See