Hubble reveals dynamic atmospheres of Uranus, Neptune

Public Release: 7-Feb-2019

Hubble reveals dynamic atmospheres of Uranus, Neptune

NASA/Goddard Space Flight Center


During its routine yearly monitoring of the weather on our solar system’s outer planets, NASA’s Hubble Space Telescope has uncovered a new mysterious dark storm on Neptune (right) and provided a fresh look at a long-lived storm circling around the north polar region on Uranus (left). Credit NASA, ESA, A. Simon (NASA Goddard Space Flight Center), and M.H. Wong and A. Hsu (University of California, Berkeley)

During its routine yearly monitoring of the weather on our solar system’s outer planets, NASA’s Hubble Space Telescope has uncovered a new mysterious dark storm on Neptune and provided a fresh look at a long-lived storm circling around the north polar region on Uranus.

Like Earth, Uranus and Neptune have seasons, which likely drive some of the features in their atmospheres. But their seasons are much longer than on Earth, spanning decades rather than months.

The new Hubble view of Neptune shows the dark storm, seen at top center. Appearing during the planet’s southern summer, the feature is the fourth and latest mysterious dark vortex captured by Hubble since 1993. Two other dark storms were discovered by the Voyager 2 spacecraft in 1989 as it flew by the remote planet. Since then, only Hubble has had the sensitivity in blue light to track these elusive features, which have appeared and faded quickly. A study led by University of California, Berkeley, undergraduate student Andrew Hsu estimated that the dark spots appear every four to six years at different latitudes and disappear after about two years.

Hubble uncovered the latest storm in September 2018 in Neptune’s northern hemisphere. The feature is roughly 6,800 miles across.

To the right of the dark feature are bright white “companion clouds.” Hubble has observed similar clouds accompanying previous vortices. The bright clouds form when the flow of ambient air is perturbed and diverted upward over the dark vortex, causing gases to freeze into methane ice crystals. These clouds are similar to clouds that appear as pancake-shaped features when air is pushed over mountains on Earth (though Neptune has no solid surface). The long, thin cloud to the left of the dark spot is a transient feature that is not part of the storm system.

It’s unclear how these storms form. But like Jupiter’s Great Red Spot, the dark vortices swirl in an anti-cyclonic direction and seem to dredge up material from deeper levels in the ice giant’s atmosphere.

The Hubble observations show that as early as 2016, increased cloud activity in the region preceded the vortex’s appearance. The images indicate that the vortices probably develop deeper in Neptune’s atmosphere, becoming visible only when the top of the storm reaches higher altitudes.

The snapshot of Uranus, like the image of Neptune, reveals a dominant feature: a vast bright stormy cloud cap across the north pole.

Scientists believe this new feature is a result of Uranus’ unique rotation. Unlike every other planet in the solar system, Uranus is tipped over almost onto its side. Because of this extreme tilt, during the planet’s summer the Sun shines almost directly onto the north pole and never sets. Uranus is now approaching the middle of its summer season, and the polar-cap region is becoming more prominent. This polar hood may have formed by seasonal changes in atmospheric flow.

Near the edge of the polar storm is a large, compact methane-ice cloud, which is sometimes bright enough to be photographed by amateur astronomers. A narrow cloud band encircles the planet north of the equator. It is a mystery how bands like these are confined to such narrow widths, because Uranus and Neptune have very broad westward-blowing wind jets.

Both planets are classified as ice giant planets. They have no solid surface but rather mantles of hydrogen and helium surrounding a water-rich interior, itself perhaps wrapped around a rocky core. Atmospheric methane absorbs red light but allows blue-green light to be scattered back into space, giving each planet a cyan hue.

The new Neptune and Uranus images are from the Outer Planet Atmospheres Legacy (OPAL) program, a long-term Hubble project, led by Amy Simon of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, that annually captures global maps of our solar system’s outer planets when they are closest to Earth in their orbits. OPAL’s key goals are to study long-term seasonal changes, as well as capture comparatively transitory events, such as the appearance of Neptune’s dark spot. These dark storms may be so fleeting that in the past some of them may have appeared and faded during multi-year gaps in Hubble’s observations of Neptune. The OPAL program ensures that astronomers won’t miss another one.

These images are part of a scrapbook of Hubble snapshots of Neptune and Uranus that track the weather patterns over time on these distant, cold planets. Just as meteorologists cannot predict the weather on Earth by studying a few snapshots, astronomers cannot track atmospheric trends on solar system planets without regularly repeated observations. Astronomers hope that Hubble’s long-term monitoring of the outer planets will help them unravel the mysteries that still persist about these faraway worlds.

Analyzing the weather on these worlds also will help scientists better understand the diversity and similarities of the atmospheres of solar-system planets, including Earth.



46 thoughts on “Hubble reveals dynamic atmospheres of Uranus, Neptune

  1. Neptune is a decent analog for study of solar irradiance changes on cryo-cold gas planets. It seems well-behaved to what we Earthlings can understand.

    Uranus is not, with its 97degree tipped over axis. It’s an odd-ball. It’s polar regions receives more sunlight than the equator, but the equator is apparently warmer. No one knows why. Its orbital eccentricity (at +/- 1.5 AU) is higher than any other planet except the dwarf-planet Pluto, again another reason Uranus is an oddball.

    So in summation, who wants to study Uranus?
    (bad joke, I know)

  2. It is absolutely amazing that man has placed a telescope in orbit of our planet earth. The discoveries that await us are unimaginable. To say that any scientific discovery or question is “settled” defies our collective understanding of what science is.

    • The most amazing telescopes IMO are the ones being built right here on planet Earth.
      Not optical, not gamma ray, x-ray, UV, IR, nor radio. But gravity. Einstein’s Gravitational Waves.
      With an ability to slice through our sun like it was butter.
      The Long-baseline Gravitational Wave Interferometors (LIGO). The ALIGO O3-run starts in March 2019.

  3. I think the information in this article is fascinating. It shows that we cannot predict what we will find in a remote place like one of the outer planets. The findings are unusual enough, and on a large enough scale, that so far no credible explanation covers them; scientists will have to continue observing, which (of course) is what real scientists do.

    Of course, whatever happens, I blame SUVs.

  4. Is this the first time a EurekAlert! release was not complete and utter bunk? Maybe I’m missing something. Were they hacked by a scientist?

    Of course studying Uranus and Neptune to better understand Earth is similar to gaining insights on avoiding birth defects by studying tube worms.

    • Yes, MarkW, that’s a challenge for you to show how in fact tube worm study dramatically contributed to the understanding of human birth defects

        • You have an endearing habit of always pointing out how any analogy is not really correct, is all. I was just poking a little fun. Not to offend.

      • Of course…if you want to discover how brainless humans assumed power via climate change science/enviro-activism, you need to study something else with no brain…
        It’s a no-brainer

    • You could look it up, Adrian. But the answer is Uranus is a bit less than earth at 89% and Neptune a bit more at 114% of earth’s gravity. Why do you ask that?

  5. “…giving each planet a cyan hue…”

    I have seen both planets through a 24 inch reflector (The UofU had one atop the physics building) and while my impression of Neptune is that it was a cornflower blue, Uranus was distinctly pea green. No one could have confused the two, but in this pair of photos one could easily mistake one for the other based on color. Anyone else weigh in on this discrepancy?

  6. I would appreciate you not writing about the atmosphere around Myanus. But if You mist know when I realease a had giant there are large methane and sulphuric components.

  7. I have long been puzzled by what seems a glaring omission in NASA’s solar system exploration program. As impressive as fly-by’s and long-range photographs are, when are they going to put permanent satellites around other planets? The uptick in data available would be astounding.

    • There are tons of reasons. First the speed has to be pretty significant to get to the gas giants in a reasonable amount of time. It would be difficult to slow something down enough to make a calm landing. Secondly it is more difficult to get a more massive probe to such distances. Technology hasn’t helped this much. Third, with Mars, we have a reasonable idea about the surface, with Triton, and other satellites, we don’t so it would be difficult to know a good landing spot. It would probably land in some methane sea. There is the issue of cold. In space, even though it is cold the relative vacuum allows the satellite to stay warm. On a moon the bitter cold methane atmosphere would almost instantly freeze up the works. Finally we can get a signal from such a distance because the signal is also in a vacuum. On the moon, I would suspect much of the signal would be lost due to the atmosphere/electrical noise, and we would not be able to communicate.

      Other than that, why not?

      • I think he said satellite, not lander/rover. What are the difficulties/impediments to that? Fuel to slowdown? As a satellite you’d keep the vacuum for communication and insulation.

        • Alex;

          Yes, that’s the point I was driving at. It can’t be that much of a technical challenge. Someone needs to smack them up the side of the head with a phone book and get their attention.

          • Galileo orbited Jupiter for 8 years. The EU Space Agency landed a probe on Titan, and received information from it for 90 minutes after its soft landing.

            We’ve done some cool stuff, but need to do more.

  8. >>
    It’s unclear how these storms form. But like Jupiter’s Great Red Spot, the dark vortices swirl in an anti-cyclonic direction . . . .

    On Earth, an anti-cyclone is a high-pressure area. They aren’t known for storms–but fair weather. Yet on the gas giants (and ice-giants), they are referred to as storm systems.



  9. Hubble has “old” hardware, but the processing of the data continues to improve and new discoveries being made. What an investment!

  10. When a tree falls in the forest, does it make a noise when there is no one there to hear it? Emphatically yes!

    • Not so fast. Quantum physics says there is not even a physical tree, only a probability distribution of a potential tree, without an observer!

      • I see why Albert Einstein wasnt satisfied with the statistical “realities” his theories had wrought. This is precisely the sort of thinking “progressives” exploit to free up logic to accommodate “truths” to be what they would like them to be and argue they are equally valid.

        This is precisely why physics is tangled in fanciful strings. This is precisely why it is stulted in the Dark Matter theory “patch” instead of trying to refine gravity theory to include its application to the vast dynamic masses and distances associated with galaxies.

        The variety of seemingly independent forces that emanate from and bind a tiny bit of matter that cry out for unification has proved quite refractory to thought. Why would a ‘throwing-up-of-arms’ Dark Matter patch to the big bit of matter satisfy?

        Why would we call upon statistics that was invented to deal with stuff we couldnt figure out otherwise to answer the silly question of whether a falling tree in a forest made a noise if it happened unobserved? Can you see how this makes us unfit to argue the merits of glibal warming theory?

        • We’re jes geeks avin a larf, Gary. Some of us might still be fit to argue the merits of global warming theory.

        • Actually, attempts have been (and are still being) made to obviate the “dark” matter problem by assuming gravity to work differently at galactic scales (MOND et al.). No workable theory has been devised,

    • A profound question. What is noise? It is the vibration of gas molecules. Animals and sound detecting devices can hear and record sound. But in the absence of a human observer with reasonable hearing range, we can only rely on previous observations that falling trees make a sound. But consider a tree collapsing slowly into a snowdrift. Would it make a noise within human hearing range? Or the other extreme of the Tunguska explosion. Is the fall of a single tree within the tumult of noise detectable?

  11. Wait. Methane is 84 times more potent than CO2 as a greenhouse gas. Shouldn’t these planets be experiencing a runaway greenhouse effect?

  12. “NASA’s Hubble Space Telescope has…provided a fresh look at a long-lived storm circling around the north polar region on Uranus.”

    Look at that polar vortex wobble during low solar activity. (Maybe.)

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