Uranus grows a smoggy cap while Jupiter's Red Spot keeps shrinking, Hubble telescope reveals

The Hubble Space Telescope monitors the big planets of the solar system's steadily varying weather.

New Hubble Space Telescope pictures of Uranus and Jupiter show how the weather steadily shifts on these massive, far-off worlds.

The atmospheres of the planets in the distant solar system are generally more steady than the weather on Earth, which varies from day to day. These worlds have very little solar illumination, and one rotation takes years to decades. The atmospheres of these worlds are still visible when scientists examine Hubble Space Telescope images taken of them several years apart.

For instance, Hubble pictures of the ice behemoth Uranus from 2014 and 2022 show that as the planet approaches its northern summer, a cap of frozen smog is expanding over its north pole. As one year on the planet lasts an astounding 87 Earth years, Uranus' seasons last more than 20 years each.

The Space Telescope Science Institute describes the white cap seen in the 2022 picture as "photochemical haze," which is comparable to the smog that develops above big towns on Earth and is full of air pollution. Hubble has observed this cap's development for a number of years and noticed that it was becoming brighter. Even though Uranus is far away and its seasons are lengthy, scientists are still working to comprehend the chemical processes that lead to the creation of this cap. In 2028, the globe will experience its subsequent summer solstice. In the 1940s, scientists last had the opportunity to view the planet at this time of the year.

Since Uranus spins around an axis that is only 8 degrees off its circular plane, differences between its seasons are thought to be extremely pronounced. That implies that the earth is almost on its side. As a consequence, during their respective winter seasons, Uranus' two regions receive very little sunlight.

Interesting weather patterns were also visible in Jupiter's images, the biggest planet in our solar system. The famed Great Red Spot of the gas giant, captured in the most recent Hubble images from earlier this year, is at its lowest size since frequent monitoring started 150 years ago. The Great Red Spot is a massive storm that is presently twice the size of Earth and swirls in the planet's southern region. The storm's perimeter experiences wind velocities of up to 425 mph (430 to 680 kph). However, the Hubble observations indicate that a new huge storm may be developing north of Jupiter's equator, even though this iconic storm may be weakening.

The new stormy area is known by astronomers as "vortex street" because it is made up of a line of interconnected cyclones that rotate in opposite directions. These cyclones could combine to form a megastorm that is even more powerful than the Great Red Spot. However, according to the Space Telescope Science Institute, which oversees Hubble's scientific activities, scientists believe that this merger is highly improbable.

Since the telescope's arrival in Earth orbit in the early 1990s, Hubble has been monitoring Jupiter, but it wasn't until this decade that researchers noticed the development of the storms that make up the "vortex street."