Scientists discover a huge energy imbalance on Saturn

A discovery by researchers at the University of Houston has revealed a massive 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 the publication Nature communication.

“This is the first time that a global energy imbalance has been observed on a seasonal scale at a gas giant,” said Liming Li, professor of physics in the UH College of Natural Sciences and Mathematics. “This not only gives us new insight 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 probe emission, Xinyue Wang, a third-year doctoral student in NSM’s Department of Earth and Atmospheric Sciences, discovered a significant and previously unknown seasonal energy imbalance on Saturn.

“Each planet receives 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 another energy input in the form of deep internal heat that affects its thermal structure and climate.”

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

“The Earth has a measurable energy budget, but that is mainly determined by the solar energy absorbed and the thermal energy emitted,” says Xun Jiang, professor of atmospheric sciences. “Earth’s internal heat is negligible and seasons last only a few months compared to seasons that last several years on Saturn.”

The data also suggests that Saturn’s unbalanced energy budget plays a key role in the development of giant storms, a 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 yet been fully explored, so we plan to investigate that as well to see if there is a connection,” Wang said.

The Cassini mission, an ambitious partnership between NASA, the European Space Agency and the Italian Space Agency, was launched in 1997 and explored Saturn and its rings and moons for almost two decades. Professor Li was chosen as a participating scientist to monitor three onboard instruments that observed Saturn’s radiant energy budget.

Wang, along with fellow students Larry Guan (Physics) and Thishan D. Karandana G and Ronald Albright (Earth and Atmospheric Sciences), conducted the research, advised by Professors Li and Jiang.

“Current models and theories of the atmosphere, climate and evolution of the gas giants assume that the global energy budget is in balance,” Wang said. “But we believe our discovery of this seasonal energy imbalance necessitates a reevaluation of those models and theories.”

Li’s team now has its sights set on the other gas giants, including Uranus, where a flagship probe mission is planned in the next decade.

“Our data suggests that these planets will also have significant energy imbalances, especially Uranus, which we predict will have the strongest imbalance due to its orbital eccentricity and very high obliquity,” Wang said. “What we investigate now will identify limitations in current observations and formulate testable hypotheses that will benefit the future flagship mission.”

In addition to UH researchers, the study 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.