Hubble Watches The Seasons Change On Saturn

One of the most beautiful planets in our solar system is Saturn, with its extensive ring system and colorful atmosphere. NASA has been observing Saturn with the Hubble Space Telescope and watching the seasons change on the massive planet. The telescope has been giving astronomers a look at the turbulent atmosphere as Saturn's northern hemisphere, currently in summer, transitions to the fall.

The three images below show Saturn in 2018, 2019, and 2020 from left to right. Planetary scientist Amy Simon from the NASA Goddard Space Flight Center says that the small year-to-your changes in Saturn's color bands are fascinating. As the planet moves towards fall in the northern hemisphere, the polar and equatorial regions are visibly changing the image sequence.

Simon also notes that scientists see the atmosphere of the planet vary on much shorter timescales. The team found that a slight change in Saturn's color from year-to-year also possibly indicated a change in cloud height and winds. However, the changes in the planet aren't huge. Scientists do expect big changes on a seasonal timescale, with the current progression showing changes towards the new season.

Images from Hubble show that from 2018 to 2020, Saturn's equator brightened by 5 to 10 percent, and winds changed slightly. In 2018, winds measured near the equator on the planet were at about 1000 miles per hour. That windspeed was significantly higher than 800 miles per hour measured by the NASA Cassini spacecraft in 2004 through 2009.

However, in 2019 and 2020, wind speeds went back to the 800 miles per hour range seen by Cassini. Wind speed also varies with altitude leading scientists to believe that the measured speed could indicate clouds in 2018 were around 37 miles deeper than those measured by Cassini. It's also worth noting that it takes Saturn 29 Earth years to complete an orbit of the sun, which means each Saturn season is more than seven years long.