During its seven-year Solstice mission, Cassini witnessed a massive storm breaking out and circling Saturn. Scientists believe such storms are partly related to the seasonal effects of sunlight on Saturn’s atmosphere. Image credit: NASA/JPL-Caltech/Institute of Space Science
Huge storms left their mark on Saturn’s atmosphere for centuries.
Researchers have discovered Saturn’s long-term giant storms, similar to Jupiter’s Great Red Spot, by studying radio emissions and interference with ammonia gas. This research reveals significant differences in atmospheres between the gas giants, challenges current understanding of giant storms, and provides new insights that may influence future studies on exoplanets.
The Great Red Spot and new discoveries on Saturn
The biggest storm in the solar system, a 10,000 mile wide anticyclone known as the Great Red Spot, has been dotting Jupiter’s surface for hundreds of years.
A new study reveals that Saturn, despite its more modest appearance compared to Jupiter’s colorful appearance, also has giant long-lasting storms. These storms have a profound effect on the atmosphere that lasts for centuries.
Study methodology
The research was carried out by astronomers at the University of California, Berkeley and the University of Michigan Ann Arbor. They examined radio emissions from the planet, which originate below the surface, and found long-term disturbances in the distribution of ammonia gas.
The study is published Aug. 11 in the journal Scientific progress.
This radio image of Saturn was taken with the VLA in May 2015, with the brighter radio emission from Saturn and its rings reduced to increase the contrast in the fainter radio emission between different latitudes in the atmosphere. Because ammonia blocks radio waves, the bright features indicate areas where ammonia is depleted and the VLA can see deeper into the atmosphere. The broad bright bands in northern latitudes are the result of a 2010 storm on Saturn, which appeared to deplete ammonia gas beneath the ammonia ice clouds we see with the naked eye. Credits: RJ Salt and ED Butter
The nature of mega storms
Giant storms occur every 20 to 30 years on Saturn and are similar to hurricanes on Earth, although much bigger. But unlike Earth’s hurricanes, no one knows why such massive storms occur in Saturn’s atmosphere, which is composed mainly of hydrogen and helium with traces of methane, water and ammonia.
“Understanding the mechanics of the solar system’s largest storm places hurricane theory within a wider cosmic context, challenging our current knowledge and pushing the boundaries of terrestrial meteorology,” said lead author Cheng Li, a former UCLA 51 Peg b fellow. Berkeley, and is now an assistant professor at the University of Michigan.
exploration and tools
Imke de Pater, UC Berkeley Emeritus Professor of Astronomy and Earth and Planetary Sciences, has studied the gas giant for more than four decades to better understand its composition and what makes it unique, using the Karl G. Jansky Very Large Array in New Mexico to investigate radio emissions from within this planet. .
On the visual plane, Saturn’s banded atmosphere appears to shift smoothly from one color to another. But seen here in radio light — the VLA data overlaid on the Cassini image of Saturn — the distinct nature of the bands is obvious. Scientists used the VLA data to better understand the ammonia in the gas giant’s atmosphere and learned that giant storms transport ammonia from the upper atmosphere to the lower atmosphere. Credit: S. Dagnello (NRAO/AUI/NSF), I. de Pater et al (UC Berkeley)
“At radio wavelengths, we investigated beneath the cloud cover seen on giant planets. Because chemical reactions and dynamics would change the composition of a planet’s atmosphere, observations below these cloud layers were needed to delimit the actual composition of a planet’s atmosphere, which is key.” parameters for models of planet formation.” “Radio observations help characterize dynamic, physical and chemical processes including heat transfer, cloud formation and convection in the atmospheres of giant planets at both global and local scales.”
Surprising results
As reported in the new study, UC Berkeley graduate student Chris Moeckel, de Pater, found something surprising in the planet’s radio emissions: an anomaly in the concentration of ammonia in the atmosphere, which they linked to an earlier major storm event in the Northern Hemisphere. from this planet.
Effects on ammonia concentration and atmospheric differences
According to the team, ammonia concentrations are lower at intermediate altitudes, below the top layers of ammonia and ice clouds, but become richer at lower altitudes, 100 to 200 kilometers deeper into the atmosphere. They believed that ammonia was transported from the upper atmosphere to the lower atmosphere through processes of precipitation and re-evaporation. Moreover, this effect can last for hundreds of years.
Comparing Saturn and Jupiter
Further study revealed that although both Saturn and Jupiter are made of hydrogen gas, the two gas giants are very different. Although Jupiter has tropospheric anomalies, they are bound by its regions (white bands) and belts (dark bands) and are not caused by storms like on Saturn. Significant differences between neighboring gas giants challenge current understanding of the formation of giant storms on gas giants and other planets. This could also affect how these storms are found and examined on exoplanets in the future.
Reference: “Profound Long-Term Impact of Saturn’s Giant Storm” By Cheng Li, Emke de Pater, Chris Moeckel, RJ Salt, Brian Butler, David de Boer and Zhiming Zhang, 11 Aug. 2023, Available here. Scientific progress.
DOI: 10.1126/sciadv.adg9419
The National Radio Astronomy Observatory (NRAO) is a facility of the National Science Foundation, which is operated under a cooperative agreement with Associated Universities Inc.
2023-08-15 02:58:14
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