Scientists discover major energy imbalance on Saturn

Energy imbalance of Saturn. Credit: NASA/JPL.

Researchers from the University of Houston have discovered a significant energy imbalance on Saturn, which is changing our understanding of planetary science and the evolution of gas giants.

These findings, published in Nature Communications, challenge existing climate models for these massive planets.

“This is the first time we’ve observed a global energy imbalance on a seasonal scale on a gas giant,” said Liming Li, a physics professor at UH.

“This discovery gives us new insights into how planets form and evolve and changes the way we think about planetary and atmospheric science.”

The discovery was made using data from the Cassini mission, with Xinyue Wang, a third-year doctoral student in UH’s Department of Earth and Atmospheric Sciences, leading the research. Wang found a significant and previously unknown seasonal energy imbalance on Saturn.

“Planets receive energy from the sun as solar radiation and lose energy by emitting thermal radiation,” Wang explained. “Saturn, like other gas giants, also has deep internal heat that affects its thermal structure and climate.”

Saturn’s energy imbalance is due to its large orbital eccentricity, which causes significant seasonal variations in the amount of solar energy it absorbs. In contrast, Earth’s small orbital eccentricity means it does not experience such a significant seasonal energy imbalance.

“Earth’s energy budget is mainly determined by absorbed solar energy and emitted thermal energy,” said Xun Jiang, a professor of atmospheric sciences. “Earth’s internal heat is negligible, and its seasons last only a few months, unlike Saturn’s, which last several years.”

The data also suggests that Saturn’s unbalanced energy budget plays a key role in the development of giant storms, which dominate its weather system. This finding may also provide insights into weather patterns on Earth.

“We plan to investigate if the energy budget’s role in developing moist, convective storms on Earth is similar to what we see on Saturn,” Wang said.

The Cassini mission, launched in 1997 by NASA, the European Space Agency, and the Italian Space Agency, explored Saturn and its rings and moons for nearly 20 years. Professor Li was a participating scientist, monitoring instruments that observed Saturn’s energy budget.

Wang, along with graduate students Larry Guan, Thishan D. Karandana G, and Ronald Albright, conducted the study under the guidance of professors Li and Jiang.

“In current models of gas giant atmospheres and climates, the global energy budget is assumed to be balanced,” Wang said. “Our discovery of this seasonal energy imbalance means we need to reevaluate those models.”

Li’s team plans to study other gas giants, including Uranus, where a flagship probe mission is planned in the next decade.

“We predict significant energy imbalances on these planets, especially Uranus due to its unique orbital characteristics,” Wang said. “Our current work will help identify limitations in existing observations and develop new hypotheses for future missions.”

The study also included contributions from scientists at NASA, the University of Wisconsin, the University of Maryland, the University of Central Florida, the University of California, Santa Cruz, as well as researchers from France and Spain.

Source: University of Houston.