Hubble telescope observes strange 'pitch black' planet

This artist’s impression shows the exoplanet WASP-12b — an alien world as black as fresh asphalt, orbiting a star like our Sun. Scientists were able to measure its albedo: the amount of light the planet reflects. The results showed that the planet is extremely dark at optical wavelengths. CREDIT NASA, ESA, and G. Bacon (STScI)


Astronomers have discovered that the well-studied exoplanet WASP-12b reflects almost no light, making it appear essentially pitch black. This discovery sheds new light on the atmospheric composition of the planet and also refutes previous hypotheses about WASP-12b’s atmosphere. The results are also in stark contrast to observations of another similarly sized exoplanet.

Using the Space Telescope Imaging Spectrograph (STIS) on the NASA/ESA Hubble Space Telescope, an international team led by astronomers at McGill University, Canada, and the University of Exeter, UK, have measured how much light the exoplanet WASP-12b reflects — its albedo — in order to learn more about the composition of its atmosphere [1].

The results were surprising, explains lead author Taylor Bell, a Master’s student in astronomy at McGill University who is affiliated with the Institute for Research on Exoplanets: “The measured albedo of WASP-12b is 0.064 at most. This is an extremely low value, making the planet darker than fresh asphalt!” This makes WASP-12b two times less reflective than our Moon which has an albedo of 0.12 [2]. Bell adds: “The low albedo shows we still have a lot to learn about WASP-12b and other similar exoplanets.”

WASP-12b orbits the Sun-like star WASP-12A, about 1400 light-years away, and since its discovery in 2008 it has become one of the best studied exoplanets (opo1354-, opo1015-, opo1436-, heic1524- With a radius almost twice that of Jupiter and a year of just over one Earth day, WASP-12b is categorised as a hot Jupiter. Because it is so close to its parent star, the gravitational pull of the star has stretched WASP-12b into an egg shape and raised the surface temperature of its daylight side to 2600 degrees Celsius.

The high temperature is also the most likely explanation for WASP-12b’s low albedo. “There are other hot Jupiters that have been found to be remarkably black, but they are much cooler than WASP-12b. For those planets, it is suggested that things like clouds and alkali metals are the reason for the absorption of light, but those don’t work for WASP-12b because it is so incredibly hot,” explains Bell.

The daylight side of WASP-12b is so hot that clouds cannot form and alkali metals are ionised. It is even hot enough to break up hydrogen molecules into atomic hydrogen which causes the atmosphere to act more like the atmosphere of a low-mass star than like a planetary atmosphere. This leads to the low albedo of the exoplanet.

To measure the albedo of WASP-12b the scientists observed the exoplanet in October 2016 during an eclipse, when the planet was near full phase and passed behind its host star for a time. This is the best method to determine the albedo of an exoplanet, as it involves directly measuring the amount of light being reflected. However, this technique requires a precision ten times greater than traditional transit observations. Using Hubble’s Space Telescope Imaging Spectrograph the scientists were able to measure the albedo of WASP-12b at several different wavelengths.

“After we measured the albedo we compared it to spectral models of previously suggested atmospheric models of WASP-12b”, explains Nikolay Nikolov (University of Exeter, UK), co-author of the study. “We found that the data match neither of the two currently proposed models.” [3]. The new data indicate that the WASP-12b atmosphere is composed of atomic hydrogen and helium.

WASP-12b is only the second planet to have spectrally resolved albedo measurements, the first being HD 189733b, another hot Jupiter. The data gathered by Bell and his team allowed them to determine whether the planet reflects more light towards the blue or the red end of the spectrum. While the results for HD 189733b suggest that the exoplanet has a deep blue colour (heic1312-, WASP-12b, on the other hand, is not reflecting light at any wavelength. WASP-12b does, however, emit light because of its high temperature, giving it a red hue similar to a hot glowing metal.

“The fact that the first two exoplanets with measured spectral albedo exhibit significant differences demonstrates the importance of these types of spectral observations and highlights the great diversity among hot Jupiters,” concludes Bell.


76 thoughts on “Hubble telescope observes strange 'pitch black' planet

    • So it is “pitch black” , “as dark as freshly poured asphalt (huh?) and glowing red. Clever little Jupiter thingy.
      Science isn’t what it used to be. Especially by the time they try to dumb it down for the unwashed masses.
      “about 1400 light-years away” , yes but how many football fields is that. You know we can’t understand any measurements if they are not expressed in football fields and olympic swimming pools.

      • For the dimensionally impaired:
        1400 ly = 48,228,066,666,666,667 football fields +/- a few
        Olympic swimming pools will be twice that number.
        but, its only a mere 429.2 parsecs (BTW it’s NOT a unit of time…no thanks to George Lucas)
        For the truly dimensionally limited its still a sh*t load. 🙂

      • @rocketsceintist : ha, you are the guy who was in charge of the computations for the “Mars Climate Orbiter” right ? lol

      • WITH the end zones it is not nearly as far: 1.207…x10^17 FF
        or Brett Favre career passing distances: 2.349…x10^14, practically next door.

      • Will,
        I suspect those are very local measurements.
        ‘End zones’ strongly suggests Canadian (Or, perhaps, American) Football Fields.
        Rather than the FIFA approved (With no corruption at all I am sure) Soccer – really (Association) Football.
        Over a billion know Kabaddi pitches.
        Go with the flow.

    • yes they seem to be confusing themselves trying to come up with something dumb enough to present to the public. If it’s glowing it clearly can not be “pitch black”.
      Scientists love being condescending they are just terribly bad at doing it.

  1. Clearly there are only 2 possible explanations:
    1. The planet is inhabited by an advanced civilization who have correctly formulated their chemtrails to ensure optimum energy capture from their star.
    2. God made it like that. He likes a bit of variety in the colour scheme.

  2. “The measured albedo of WASP-12b is 0.064 at most. This is an extremely low value, making the planet darker than fresh asphalt!” This makes WASP-12b two times less reflective than our Moon which has an albedo of 0.12 [2].
    Is this a fair comparison, seeing that our Moon shines very brightly (when full on a clear night)?

    • Exactly. Something with half the albedo of the moon will be between the white parts and the darker man in the moon. (Or rabbit in the moon, for us down under.) It will be greyish. Not jet black.

    • It shines just a brightly on a cloudy night 😉
      It may appear “bright” compared to the black of space but that is not much compared to the brightness of the sunlight hitting it.

    • Um…reflected light intensity its a distance thing (1/r/r) . The reflected light intensity is a function on how reflective the surface is (albedo) and the inverse square of the distance between the observer and the object.
      If the object were the same distance away from us as is our moon and its albedo were 1/2 that of the moon it would appear half as bright as the moon. But seeing that it is rather massive, if it were as close as the moon its brightness might be the least of our concerns.

    • The moon is actually fairly dark grey, on average. Something like asphalt that’s a few months old. It just looks bright to us because 1) we usually view it at night, and 2) the sunlight that’s illuminating it is very bright. I agree that the article is a bit misleading; while it would be darker than the moon, we wouldn’t have any trouble viewing it with the naked eye.

    • There are places on Earth that have close to 6% Albedo on a cloudless day.
      Of course, Earth is not right next to its star so it is a big difference in terms of energy accumulation/equilibrium stored level.

  3. WASP-19b is certainly getting a lot of attention this week. I assume the Hubble team will publish a paper on their findings – a good college teacher should grab copies of both of them for their astrophysics classes. A good example of real science, that doesn’t have a “consensus” (at least not yet). The two artist’s conceptions could introduce the instructional unit: “Same planet, two very different ideas about it.”
    If that temperature reading proves correct, there will probably be some good work done on the dynamics between the solar and planetary atmospheres, too. Something to keep an eye on, certainly.

  4. “With a radius almost twice that of Jupiter and a year of just over one Earth day, WASP-12b is categorised as a hot Jupiter.”
    I think I’m more impressed by a 24 hour year than it being so dark.

  5. Yet another very speculative report about exo-planets that are not really “observed” in the way you or I would mean.
    All of the images and links to other pages feature “artist’s renditions” of what someone thinks the data retrieved by Hubble might mean. There are no images shown — because there are no images.
    i am no convinced by any of this stuff.

    • Nor I, Kip. But I just spent a half hour of google fu figuring out why before commenting just below. Answer lies in the dissassociation energy of molecular to atomic hydrogen. H forms molecules of H2 for a reason. Same as N2, O2, all other except noble gasses like helium (OK, excepting weak VanderWall force binding). Always nice to find out why the intuitive scratch and sniff test is directiinally correct or incorrect. Neat little piece of obscure physics directly junks this garbage paper

    • “All of the images and links to other pages feature “artist’s renditions” of what someone thinks the data retrieved by Hubble might mean. There are no images shown — because there are no images.”
      Indeed. That was disappointing…

    • “Kip Hansen September 15, 2017 at 2:27 pm”
      Agreed! To me it sounds more like presenting “findings” from their research. Budget cuts looming?

  6. Color me VERY skeptical. 1. A planet with such low albedo that far away has little to no detectible optical signature, period, especially that close to its own Sun. All noise, no data. 2. (Killer physics) Very hot atomic hydrogen disassociates from molecular hydrogen (Gibbs free energy analysis, the so called theoretical Saha equation for this specific disassociation in astrophysics) is ~50,000K. Under non-ideal turbulent conditions maybe 10400K average temp where local conditions exceed 50,000K. Easy Google to many peer reviewed papers on this astrophysics conundrum. BUT, The surface of our Sun averages~ 5800K. And it is anything but black. Flunk the Masters student on ignorance of basic atomic/molecular physics.

  7. Maybe what they have detected is not a planet. What if WASP-12 is a binary star system and what has been detected is the burned out remains of the dwarf of the pair, in a decaying orbit, headed to eventual doom. Would we be able to tell the difference at 1400ly?

  8. From what I have read on this so far, there is nothing even remotely close to conclusive in the results, it’s all interpretation and guesses.
    Granted it’s the best we can do but my god does science media then write it up as seeming even remotely certain in anything other than the fact there is a planet and it is close to the star.
    For all we know it has thousands of ash spewing volcanoes because of the gravitational effects on the planet, hence it’s dark and hot.

  9. What………….
    They really have not explained themselves well here at all.
    Things that are ‘red hot’ are typically about 500 degC .. ish
    By the time they get to 2000 C, to our eyes they become ‘white hot’ – just try venturing into a steelworks without wearing dark glasses or a welding mask.
    But then, what the object actually emits (radiates because of its temp) is not the definition of albedo (what it reflects)
    So, they go on to say the ‘atmosphere’ is so hot it is ionised.
    But don’t ionised things (plasma) conduct electricity? Are plasmas not actually very good conductors?
    So any incoming radiation (electromagnetic waves) will meet a conductive surface (thing/whatever) and do like EM waves do everywhere when they meet an electrically conducting thing – invert the phase of their electric field and go right back to where they came.
    They are reflected. They see a mirror.
    This does of course open the can of worms of…
    What is the albedo of a mirror?
    Just like the albedo of melted ice (water) near the North Pole, its albedo depends on the angle you look at it.
    Is that what’s happening? When they look at this planet, they are looking at a spherical mirror. Hence the reflection of its parent star (sun) is just a very tiny dot – it’s the optics of the Mirror Ball – as used in dance halls/discos since dance-halls and discos came into being.
    The Mirror Ball (and of course flashing computer controlled lights) being a representation of the flickering fire-light our ancient ancestors used to dance around during the long dark nights of deepest Africa – where we all originated(?)
    With no tax to pay or tedious busy bodies stressing us out with endless ‘warnings’, we could enjoy ourselves and party every night.
    Nothing new under the sun, as they say, just muddled heads that can’t explain sh1t.

  10. On Wasp12b tomorrow and next year are the same. Macbeth’s ‘Tomorrow, an tomorrow, and tomrrow .. ‘ speech would be come different.. ‘ all our last years..’

  11. “Pave the world! One people one planet, one giant slab of asphalt!”
    Old T-shirt from a Paver that I knew….

  12. WASP-21 reminds me of “Hot Black” Desiato, the “Disaster Area” front man in Hitchhikers Guide to the Galaxy.

  13. The fact albedo of WASP-12b is low implies its atmospheric dynamics is not chaotic, at least not on its sunny side.
    This is because it is a proven theorem, that reproducible non equilibrium quasi stationary thermodynamic systems lend themselves to the Maximum Entropy Production Principle. If they are only in radiative contact with their environment (as all heavenly bodies are), that translates to reflecting as little light as possible, because most of the entropy production happens, when incoming short wave light gets absorbed.
    A system is reproducible if microstates belonging to the same macrostate can’t evolve into different macrostates in a short time.
    Chaotic systems, on the other hand, are irreproducible, so they are not subject to said theorem.
    For example Earth is not pitch black as seen from space, therefore its atmospheric dynamics is chaotic, that is, as a thermodynamic entity it belongs to a class of objects not understood by physics yet.
    That much about running computational models on its processes.

  14. Well the albedo of a “naked” Earth, that is without clouds, would be almost as low. And if it was completely oceanic, it would be even lower. Given all the imperfection that there is, when you try the impossible, you should not be surprised.

    • The naked Earth, without a chaotic atmosphere, yes. It would have a low albedo.
      As it is, its albedo is pretty high (~0.3). What is more interesting, it seems to be strictly regulated, becaus annual average all sky albedo of the two hemispheres is virtually the same in spite of the fact that clear sky albedo of the Southern hemisphere is much lower due to prevalence of oceans there.
      It has just as much more clouds somehow, as to make up the difference. No one knows why? Computational climate models are utterly unable to replicate the phenomenon, so regional forecast, even one of the largest possible spatial extent, fails.

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