Astronomers often refer to Saturn as the solar system’s most photogenic planet, and the Hubble Space Telescope has now captured a brand new image of the giant planet, which reveals fine details in its iconic rings. In the latest observation, Saturn’s atmosphere displays “amber colors,” which come from "summer smog-like hazes," produced in photochemical reactions driven by the solar ultraviolet radiation. Below the haze lie clouds of ammonia ice crystals, as well as deeper, unseen lower-level clouds of ammonium hydrosulfide and water. The planet’s banded structure is caused by alternating winds that result in clouds at different altitudes, at each latitude.
“Saturn's signature rings are still as stunning as ever. The latest view of Saturn from NASA's Hubble Space Telescope captures exquisite details of the ring system - which looks like a phonograph record with grooves that represent detailed structure within the rings - and atmospheric details that once could only be captured by spacecraft visiting the distant world,” says NASA in a statement.
The image shows that the trademark ring system is now tilted toward Earth, which gives viewers a “magnificent look” at the bright, icy structure. “Hubble resolves numerous ringlets and the fainter inner rings. The image reveals an unprecedented clarity only seen previously in snapshots taken by NASA spacecraft visiting the distant planet,” says NASA.
The images were taken on June 20, 2019, by Hubble’s Wide Field Camera 3 as Saturn made its closest approach to Earth, at about 845 million miles away. “Saturn is so beautiful that astronomers cannot resist using the Hubble Space Telescope to take yearly snapshots of the ringed world when it is at its closest distance to Earth. These images, however, are more than just beauty shots. They reveal a planet with a turbulent, dynamic atmosphere,” says the statement.
Hubble shows a hexagonal pattern around the planet’s north pole discovered by the Voyager 1 spacecraft in 1981. In this new observation, Hubble also spotted some of Saturn’s moons whisking around the beautiful planet, says NASA.
Saturn's appearance changes with its seasons, which occur because Saturn's equator is tilted 27 degrees with respect to the plane of its orbit around the Sun. Its stunning rings were first identified as a continuous disk around the planet by Dutch astronomer Christiaan Huygens in 1655. “325 years later, NASA’s Voyager 1 spacecraft flyby of Saturn resolved thousands of thin, fine ringlets,” says NASA.
Data from NASA’s Cassini mission suggests the rings formed 200 million years ago, roughly around the time of the dinosaurs and Earth’s Jurassic period. “The gravitational disintegration of one of Saturn’s small moons created myriad icy debris particles, and collisions today likely continually replenish the rings,” says NASA.
The latest Hubble image shows that not a lot has changed. One such intriguing feature is the long-lasting hexagon-shaped structure circling the planet's north pole. According to the scientists, the mysterious six-sided pattern, called the hexagon -- first discovered in 1981 by NASA's Voyager 1 spacecraft, and caused by a high-speed jet stream -- continues to exist on the north pole. The hexagon, say astronomers, is so large that four Earths could fit inside its boundaries. There is no similar structure at Saturn's south pole.
Other features, however, are not as long lasting. This year's Hubble offering, says NASA, shows that a massive storm in the north polar region spotted by Hubble in 2018 has disappeared. Smaller, convective storms, called super thunderheads -- such as the one just above the center of the planet's image -- also come and go. “Smaller storms pop into view like popcorn kernels popping in a microwave oven before disappearing just as quickly. Even the planet's banded structure reveals subtle changes in color,” the statement adds.
Hubble observed Saturn as part of the Outer Planet Atmospheres Legacy (OPAL) project. The OPAL obtains images of all the gas giants in our solar system every year, which is helping scientists understand the dynamics and evolution of these mysterious outer planets. In Saturn's case, astronomers will be able to monitor and track shifting weather patterns and identify other changes.