In this captivating image, orange-hued moon Io cuts through the tops of Jupiter’s vibrant clouds, casting shadows over the planet’s western edge. Hubble’s remarkable resolution allows us to spot Io’s orange-spotted surface, which is attributed to its abundance of active volcanoes. This fiery wonderland was first detected during the Voyager 1 flyby in 1979. Beneath its thin crust, Io’s interior is bathed in molten material that is periodically ejected through volcanoes. The varied color palette of Io’s surface arises from the interaction of sulfur with varying temperatures, resulting in a mesmerizing display. Credit: Science: NASA, ESA, STScI, Amy Simon (NASA-GSFC), Michael H. Wong (UC Berkeley), Image processing: Joseph DePasquale (STScI)

Forecast for gusty winds, smog

outer planets beyond[{” attribute=””>Mars do not have solid surfaces to affect weather as on Earth. And, sunlight is much less able to drive atmospheric circulation. Nevertheless, these are ever-changing worlds. And Hubble – as interplanetary meteorologist – is keeping track, as it does every year. Jupiter’s weather is driven from inside-out as more heat percolates up from its interior than it receives from the Sun. This heat indirectly drives color change cycles highlighting a system of alternating cyclones and anticyclones. Uranus has seasons that pass by at a snail’s pace because it takes 84 years to complete one orbit about the Sun. The seasons are extreme because Uranus is tipped on its side. As summer approaches in the northern hemisphere, Hubble sees a growing polar cap of high-altitude photochemical haze that looks similar to the smog over cities on Earth.

Hubble Monitors Changing Weather and Seasons at Jupiter and Uranus

Ever since its launch in 1990, NASA’s Hubble Space Telescope has been an interplanetary weather observer, keeping an eye on the largely gaseous outer planets and their ever-changing atmospheres. NASA spacecraft missions to the outer planets have given us a close-up look at these atmospheres, but Hubble’s sharpness and sensitivity keeps an unblinking eye on a kaleidoscope of complex activities over time. In this way Hubble complements observations from other spacecraft such as Juno, currently orbiting Jupiter; the retired Cassini mission to Saturn, and the Voyager 1 and 2 probes, which collectively flew by all four giant planets between 1979 and 1989.

Inaugurated in 2014, the telescope’s Outer Planet Atmospheres Legacy (OPAL) Program has been providing us with yearly views of the giant planets. Here are some recent images:

Hubble Space Telescope images of Jupiter taken on November 12, 2022 (left) and January 6, 2023 (right). Credit: Science: NASA, ESA, STScI, Amy Simon (NASA-GSFC), Michael H. Wong (UC Berkeley), Image Processing: Joseph DePasquale (STScI)

Jupiter

[left]– Jupiter forecast is stormy weather at low northern latitudes. A prominent series of alternating storms can be seen, forming a “Vortex Street” as some planetary astronomers call it. This is a wave pattern of overlapping anti-cyclones and cyclones, locked together as in a machine with alternating gears moving clockwise and counterclockwise. If the storms get close enough to each other, in the highly unlikely event of a merger, they can build an even larger storm, potentially rivaling the Great Red Spot’s current size. The graduated pattern of anticyclones and cyclones prevents the merger of individual storms. The inland activity of these storms is also seen; In the 1990s, Hubble saw no cyclones or anticyclones with internal thunderstorms, but these storms have appeared in the past decade. The strong color variations indicate that Hubble sees different cloud heights and depths as well.

Orange moon Io photobombs this view of Jupiter’s multicolored cloud tops, casting shadows over the planet’s western edge. The resolution of the Hubble telescope is so sharp that it can see Io’s orange-spotted appearance, which is associated with many active volcanoes. These volcanoes were first discovered when the Voyager 1 spacecraft flew by in 1979. The molten interior of the Moon is covered in a thin crust through which the volcanoes spew material. Sulfur takes on different colors at different temperatures, which is why the surface of Io is so colorful. This photo was taken on November 12, 2022.

[right]—Jupiter’s fabled Great Red Spot takes center stage in this view. Although this vortex is large enough to swallow the Earth, it has actually shrunk to the smallest size it has ever been in observational records dating back 150 years. Jupiter’s icy moon Ganymede can be seen passing by the giant planet at lower right. Slightly larger than the planet Mercury, Ganymede is the largest moon in the solar system. It is a cratered world with a primarily water-ice surface with visible icy outflows driven by internal heat. (This image is smaller because Jupiter was 81,000 miles from Earth when the image was taken.) This photo was taken on January 6, 2023.

Hubble Space Telescope images of Uranus taken on November 9, 2014 (left) and November 9, 2022. Credit: Science: NASA, ESA, STScI, Amy Simon (NASA-GSFC), Michael H. Wong (UC Berkeley), Image Processing: Joseph DiPasquale (STScI)

Uranus

Eccentric Uranus rolls on its side around the sun as it follows an 84-year orbit, rather than spinning in a more vertical position as Earth does. Uranus has a strangely “horizontal” axis of rotation that is only eight degrees from the plane of the planet’s orbit. One recent theory suggests that Uranus once had a massive moon that was destabilized by gravity and then collided with. Other possibilities include giant effects during planet formation, or even giant planets exerting resonant torques on each other over time. The consequences of the planet’s tilt are that, at intervals of up to 42 years, parts of the Earth’s hemisphere are completely devoid of sunlight. When the Voyager 2 spacecraft visited during the 1980s, the planet’s south pole was pointed directly toward the sun. Hubble’s latest view shows that the North Pole is now tilting toward the Sun.

[left]This is a Hubble view of Uranus taken in 2014, seven years after the northern vernal equinox when the sun was shining directly over the planet’s equator, and shows one of the first images from the OPAL programme. Multiple storms with clouds of methane ice crystals appear in mid-northern latitudes above the planet’s cyan-colored lower atmosphere. Hubble has imaged the ring system at the edge in 2007, but the rings began to bloom after seven years in this view. At this time, the planet had several small storms and even some faint cloud clusters.

[right]– As seen in 2022, Uranus’ north pole shows a thick, smog-like photochemical haze over cities. Several small storms can be seen near the edge of the polar haze boundary. Hubble has been tracking the size and brightness of the northern polar cap and it continues to get brighter year after year. Astronomers untangle the multiple influences–from atmospheric circulation, particle properties, and chemical processes–that control how the atmospheric polar cap changes with the seasons. At the European equinox in 2007, neither pole was particularly bright. As the northern summer solstice approaches in 2028, the cap may get brighter, and will point directly toward Earth, allowing good views of the rings and the North Pole; The ring system will then appear face to face. This photo was taken on November 9, 2022.

about Hubble

The Hubble Space Telescope is an amazing collaboration between NASA and the European Space Agency, which is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Delving into the mysteries of the universe, the Space Telescope Science Institute (STScI) in Baltimore leads Hubble’s science endeavours. The Association of Universities for Research in Astronomy, located in Washington, D.C., operates STScI on behalf of NASA.