Surface temperature of Pluto
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Pluto Surface Temperature Range: Key Measurements
Multiple studies have measured Pluto’s surface temperature using different methods. Most research finds that Pluto’s surface temperature generally falls between 30 K and 60 K, depending on location and surface composition. Early millimeter-wave thermal emission measurements suggest a surface temperature between 30 and 44 K, with a likely average near 35–37 K for much of Pluto’s surface, which is cooler than some earlier models predicted . Other studies using infrared and far-infrared observations have found that the surface is not isothermal, with maximum dayside temperatures reaching 54–63 K and significant diurnal variations .
Surface Temperature Variation Across Pluto
Pluto’s surface temperature is not uniform. Bright areas, which are covered by nitrogen (N2) ice, tend to be colder, with temperatures around 40 K. In contrast, the darkest regions, likely covered by irradiated methane ice and tholins, can reach up to 60 K . This variation is supported by both ground-based and spacecraft observations, as well as laboratory simulations of Pluto-like conditions 235.
Nitrogen Ice and Surface Temperature
Spectroscopic studies focusing on nitrogen ice have determined that the temperature of N2 ice on Pluto is about 40 ± 2 K . This is consistent with other findings that suggest the surface temperature is just above the alpha-beta transition phase of N2, close to 36.5 K . These cold temperatures are important for understanding the physical state of surface ices and the behavior of Pluto’s thin atmosphere.
Methane and Carbon Monoxide Ices
The presence of methane (CH4) and carbon monoxide (CO) ices also influences surface temperature. The low temperatures measured indicate that methane is present as a solid, not as a gas, and that Pluto’s atmosphere is likely dominated by nitrogen or carbon monoxide rather than methane . Laboratory experiments simulating Pluto’s surface conditions confirm that phase transitions in these ices occur within the observed temperature range of 33–55 K .
Global and Local Temperature Models
Some models suggest that Pluto’s surface could be close to 58 K globally, due to the low thermal emissivity of solid methane, which absorbs sunlight but does not radiate heat efficiently . However, other models and observations favor a lower, more variable surface temperature, with a globally uniform temperature possibly as low as 45 K . The actual temperature likely depends on local surface composition, albedo, and insolation.
Conclusion
In summary, Pluto’s surface temperature varies significantly across its surface, generally ranging from about 30 K in the coldest regions to 60 K in the warmest, with most areas near 35–44 K. These temperatures are determined by the distribution of nitrogen, methane, and carbon monoxide ices, as well as surface albedo and local sunlight. The cold surface conditions play a crucial role in the physical state of Pluto’s ices and the nature of its thin atmosphere 123457910.
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