How hot is saturn
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How Hot is Saturn?
Saturn, the sixth planet from the Sun, exhibits a complex and varied temperature profile across its atmosphere, rings, and surrounding space. This article synthesizes findings from multiple research studies to provide a comprehensive overview of Saturn's thermal characteristics.
Effective Temperature of Saturn
The effective temperature of Saturn, which is a measure of the planet's overall thermal emission, has been determined to be approximately 94.4 K1 and 96.5 K3. This temperature is significantly higher than what would be expected if Saturn were only heated by the Sun, suggesting an additional internal heat source. The high effective temperature indicates that Saturn emits more than twice the energy it absorbs from sunlight1 3.
Atmospheric Temperature Variations
Zonal Temperature Bands
Saturn's atmosphere features distinct zonal temperature bands that are largely uncorrelated with visible cloud patterns. High-resolution imaging has revealed strong temperature oscillations at certain latitudes, such as near 32°S, and a notably warm south polar cap2. The temperature at the 1-bar pressure level ranges from 137 to 140 K, with slight variations between different atmospheric belts and zones1.
Thermosphere and Upper Atmosphere
The thermosphere of Saturn, which is the uppermost layer of its atmosphere, exhibits temperatures ranging from approximately 150 K near the lower boundary to around 400 K at equatorial latitudes, increasing further to 550-600 K at the poles5. These high temperatures are primarily driven by auroral heating, which significantly exceeds the heating from solar ultraviolet radiation5. Measurements from the Cassini mission indicate that the thermospheric temperature profile can reach up to 370 K at certain altitudes6.
Polar Regions and Cyclones
Saturn's poles are characterized by hot cyclonic vortices, with temperature contrasts of about 7 K in the upper troposphere within 1.4° of both poles8. These polar hot spots extend into the stratosphere but weaken with altitude, disappearing near the 1 mbar pressure level8. The polar regions also exhibit seasonal temperature variations, with the south pole cooling dramatically and the north pole warming as the seasons change9.
Ring Temperatures
The temperatures of Saturn's rings vary depending on their exposure to sunlight. The illuminated side of the rings has temperatures ranging from 60 to 70 K, while the shadowed side ranges from less than 60 K to 67 K. The average temperature of the unilluminated north side of the rings is around 55 K1.
Hot Plasma Zone
In addition to the atmospheric and ring temperatures, a region of extremely hot plasma has been observed around Saturn. This doughnut-shaped zone, located at altitudes ranging from 273,600 km to 724,000 km above the planet's cloud tops, contains gas with temperatures ranging from 300 million to nearly 1 billion degrees Celsius4. This is the hottest gas observed in the solar system.
Conclusion
Saturn's temperature profile is highly complex, with significant variations across different atmospheric layers, latitudes, and regions. The planet's effective temperature is higher than expected due to internal heat sources, and its thermosphere and polar regions exhibit extreme temperatures driven by auroral and seasonal effects. The rings and surrounding plasma also contribute to the diverse thermal landscape of this gas giant.
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Most relevant research papers on this topic
Pioneer Saturn Infrared Radiometer: Preliminary Results
The Pioneer Saturn Infrared Radiometer has provided a preliminary estimate of the effective temperature of Saturn, indicating a total emission greater than two times the absorbed sunlight.
Saturn's Temperature Field from High-Resolution Middle-Infrared Imaging
Saturn's atmosphere shows zonal temperature bands uncorrelated with visible cloud reflectivity, strong 100-millibar zonal temperature oscillations near 32°S, a warm south polar cap, and a compact hot point within 3° of the south pole.
Highly CitedSaturn's Atmospheric Temperature Structure and Heat Budget
The high effective temperature of 96.5 2.5 K suggests that Saturn has an additional energy source besides cooling and contraction, with the high mole fraction of H_2 suggesting that separation of heavier He toward the core may supply the additional energy.
Hot plasma zone near Saturn
The hot gas is an enormous doughnut-shaped region encircling Saturn at an altitude of 273,600 km above the planet's cloud top to as high as 724,000 km.
Saturn Variable Thermosphere
Saturn's thermosphere is dominated by H2, with a potential energy crisis if not efficiently redistributed to low latitudes.
Thermal Structure and Composition of Saturn's Upper Atmosphere From Cassini/Ion Neutral Mass Spectrometer Measurements
Saturn's upper atmosphere shows temperatures from 340 to 370 K, with helium in diffusive equilibrium and CH4 in constant mixing ratio relative to H2, likely due to external material from its rings.
Temperature and Composition of Saturn's Polar Hot Spots and Hexagon
Saturn's poles exhibit unexpected symmetry in hot, cyclonic polar vortices, with cores depleted in phosphine gas, likely due to air subsidence into the troposphere.
Highly CitedThermal Emission From Saturn's Polar Cyclones
Saturn's polar cyclones show larger temperature contrasts and weaken with depth, suggesting winds decay with altitude over three pressure scale heights above 200 mbar.
Seasonal evolution of Saturn’s polar temperatures and composition
Saturn's polar temperatures and composition show seasonal variations, with the south polar stratosphere cooling and north polar stratosphere warming, suggesting changes in vertical windshear on zonal jets.
Seasonal change on Saturn from Cassini/CIRS observations, 2004–2009
Saturn's atmosphere shows seasonal changes in insolation, with northern mid-latitudes experiencing dramatic warming and southern mid-latitudes cooling, and the ring-shadowed regions showing larger temperatures than predicted by models.
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