The exoplanets beyond Mars do not have solid surfaces to affect the weather the way Earth does. Additionally, sunlight can control atmospheric circulation much less. But these worlds are constantly changing. And as an interplanetary meteorologist, Hubble watches it, as it does every year. Jupiter’s weather changes from the inside out as more heat seeps through it than it receives from the Sun. This heat indirectly activates cycles of color change, illuminating the changing cyclone and anticyclone system. Uranus has seasons that move at a snail’s pace because it takes 84 years to complete one revolution around the Sun. The seasons are extreme because Uranus is tilted. As summer approaches in the Northern Hemisphere, Hubble sees a growing polar cap made of smoke-like, high-altitude photochemical fog over Earth’s cities.

Since its launch in 1990, NASA’s Hubble Space Telescope has been an interplanetary weather observer, monitoring mostly gaseous exoplanets and their ever-changing atmospheres. NASA’s spacecraft missions to exoplanets have allowed us to see these atmospheres up close, but Hubble’s sharpness and precision unblinkingly observes a kaleidoscope of complex actions over time. In this way, Hubble complements observations of other spacecraft such as Juno currently orbiting Jupiter; Completion of the Cassini mission to Saturn and Voyager 1 and 2, which passed together by all four giant planets between 1979 and 1989.

Launched in 2014, the Outer Planetary Atmospheres Legacy (OPAL) telescope program provides us with annual images of giant planets. Here are some new images:

Jupiter

[Зліва] — Stormy weather expected for Jupiter at low northern latitudes. A distinct group of successive storms can be seen forming a “vortex street,” as some planetary astronomers call it. It is a wave pattern of interconnected interlocking anticyclones and cyclones, as in a machine with variable gears that move clockwise and counterclockwise. If the storms get close enough together, in the unlikely event of a merger, they could create an even larger storm that could potentially compete with the current size of the Great Red Spot. The checkerboard distribution of anticyclones and cyclones prevents separate storms from merging. Activity is also seen in these storms; In the 1990s, Hubble did not see any cyclones or anticyclones with thunderstorms, but these storms have emerged in the last decade.

The orange moon Io photobombs this image of Jupiter’s colorful cloud tops, casting a shadow over the planet’s west wing. Hubble’s resolution is so high that it can see the mottled orange appearance associated with many of Io’s active volcanoes. These volcanoes were first discovered in 1979 when the Voyager 1 spacecraft passed by them. The Moon’s molten interior is covered with a thin crust from which volcanoes eject material. Sulfur takes on different hues at different temperatures, so the surface of Io is very colorful. This image was taken on November 12, 2022.

[Праворуч] — Jupiter’s legendary Great Red Spot is in the center of this image. Although this vortex was large enough to swallow the Earth, it actually shrunk to the smallest size observed 150 years ago. In the lower right corner, Jupiter’s icy moon Ganymede is seen passing through the giant planet. Slightly larger than the planet Mercury, Ganymede is the largest moon in the Solar System. It is a cratered world with a mostly water-ice surface, with obvious internal heat-induced ice flows. (This image is smaller because Jupiter was 81,000 miles further away from Earth when the photo was taken.) This image was taken on January 6, 2023.

Uranus

Rather than orbiting in a more vertical position as Earth does, planetary-strange Uranus orbits the Sun on its side, following an 84-year orbit. Uranus’ axis of rotation is oddly inclined “horizontally” at an angle of only eight degrees from the planet’s orbital plane. A recent theory suggests that Uranus was once a giant moon that gravitationally destabilized it and then crashed into it. Other possibilities include giant collisions during planet formation, or even giant planets impacting each other at a resonance moment in time. The effects of the planet’s tilt are that parts of a hemisphere are completely deprived of sunlight for periods of up to 42 years. When the Voyager 2 spacecraft visited the planet in the 1980s, the planet’s south pole was almost directly facing the Sun.

[Зліва] — This is a Hubble image of Uranus taken in 2014, seven years after the vernal equinox, when the Sun was shining directly above the planet’s equator, and shows one of the first images from the OPAL program. At mid-northern latitudes, numerous methane ice cloud storms appear with a blue hue above the planet’s lower atmosphere. Hubble took a side photo of the ring system in 2007, but this image shows the rings starting to open seven years later. At this time, there were several small storms and even a few weak cloud bands on the planet.

[Праворуч] — As seen in 2022, Uranus’ north pole shows a thick photochemical haze that resembles smoke over cities. A few small storms can be seen near the edge of the polar haze boundary. Hubble tracks the size and brightness of the polar cap and continues to get brighter each year. Astronomers are unraveling the many effects that control how the atmospheric polar cap changes with the seasons, such as atmospheric circulation, particle properties, and chemical processes. During the Uranian equinox in 2007, neither pole was particularly bright. As the northern summer solstice approaches in 2028, the cap may become even brighter, pointing directly at Earth, providing a good view of the rings and the north pole; the ring system will appear on the front. This image was taken on November 9, 2022.