Scientists have discovered a massive energy imbalance on Saturn

A discovery by University of Houston researchers has revealed a huge energy imbalance on Saturn, shedding new light on planetary science and evolution and challenging existing climate models for the solar system’s gas giants. The findings appear in a publication The nature of communication.

“This is the first time a global energy imbalance on a seasonal scale has been observed in a gas giant,” said Liming Li, professor of physics in the UH College of Natural Sciences and Mathematics. “Not only does it give us new insights into the formation and evolution of planets, but it also changes the way we should think about planetary and atmospheric science.”

Using data from the Cassini mission, Xinyue Wang, a third-year doctoral student in NSM’s Department of Earth and Atmospheric Sciences, found a significant and previously unknown seasonal energy imbalance on Saturn.

“Each planet gains energy from the sun in the form of solar radiation and loses energy by emitting thermal radiation,” Wang said. “But Saturn, like the other gas giants, has an additional energy input in the form of deep internal heat affecting its thermal structure and climate.”

The imbalance is caused by the large eccentricity of Saturn’s orbit, which varies by nearly 20% from aphelion (the point on the orbit furthest from the Sun) to perihelion (the point on the orbit closest to the Sun), resulting in huge seasonal variations in absorbed solar energy. . Unlike Saturn, Earth does not experience a significant seasonal energy imbalance due to its very small orbital eccentricity.

“Earth has a measurable energy budget, but it is primarily determined by absorbed solar energy and emitted thermal energy,” said atmospheric sciences professor Xun Jiang. “Earth’s internal heat is negligible, and its seasons last only a few months compared to Saturn’s seasons that are several years long.”

The data also suggest that Saturn’s unbalanced energy budget plays a key role in the development of giant storms, which are the dominant weather phenomenon in the planet’s atmospheric system. This data can also provide some insight into Earth’s weather.

“To our knowledge, the role of the energy budget in the development of moist, convective storms on Earth has not been fully explored, so we plan to explore that as well to see if there is a connection,” Wang said.

The Cassini mission, an ambitious joint effort between NASA, the European Space Agency and the Italian Space Agency, was launched in 1997 and has explored Saturn and its rings and moons for nearly 20 years. Professor Li was selected as a participating scientist to monitor three onboard instruments that monitored Saturn’s energy budget.

Wang, along with fellow graduate students Larry Guan (Physics) and Thishan D. Karandana G and Ronald Albright (Earth and Atmospheric Sciences), conducted the study based on the recommendations of Professors Li and Jiang.

“In current models and theories of the atmosphere, climate and evolution of gas giants, the global energy budget is assumed to be balanced,” Wang said. “But we believe that our discovery of this seasonal energy imbalance calls for a rethinking of these models and theories.”

Li’s team is now targeting other gas giants, including Uranus, where a flagship mission is planned for the next decade.

“Our data suggest that these planets will also have a significant energy imbalance, especially Uranus, which we predict will have the strongest imbalance due to its orbital eccentricity and very high obliquity,” Wang said. “What we are investigating now will reveal limitations in current observations and formulate testable hypotheses that will benefit future flagships.”

In addition to the UH scientists, the study’s authors include scientists from NASA, the University of Wisconsin, the University of Maryland, the University of Central Florida and the University of California, Santa Cruz, as well as scientists from France and Spain.