Surface temperature of mercury
Pro Research Analysisby 
Searched over 200M research papers
Surface Temperature Range on Mercury
Mercury experiences some of the most extreme surface temperature variations in the solar system. At the equator, surface temperatures can drop to less than 100 K (about -173°C) during the night and rise up to 700 K (about 427°C) at local noon, especially at longitudes 0° W and 180° W, which coincide with Mercury’s closest approach to the Sun (perihelion). At other longitudes (90° W and 270° W), the maximum temperature at local noon is slightly lower, reaching up to 570 K (about 297°C) due to Mercury’s unique 3:2 spin-orbit resonance. At 45° N latitude, local noon temperatures reach 645 K at perihelion longitudes and 510 K at aphelion longitudes .
Subsolar and Night-Side Temperatures
The subsolar point, which is the point directly facing the Sun, can reach temperatures of around 407 K, depending on Mercury’s distance from the Sun . Observations from Mariner 10 and other missions confirm that the minimum predawn surface temperature at the warm pole (longitude 270°) is near 93 K . The average temperature on the dark side of Mercury is about 111 K, which is similar to the surface temperature of the Moon’s night side, indicating low thermal inertia and a thin or absent atmosphere .
Polar Temperatures and Permanently Shadowed Regions
Despite Mercury’s proximity to the Sun, the poles remain much colder. Flat, low-reflectivity surfaces at the poles do not exceed 167 K, and in permanently shadowed regions within large craters, temperatures can be as low as 60 K. These cold conditions allow water ice to remain stable over billions of years in these shadowed craters .
Surface Temperature Effects on Mercury’s Surface Properties
High equatorial temperatures on Mercury can cause changes in the surface reflectance due to thermal annealing, where nanophase metal particles grow into larger particles, resulting in a darker surface. Surfaces with maximum temperatures above 675 K are observed to be 7–12% darker than those with maximum temperatures below 473 K, especially in smooth plains. This darkening correlates with temperature variations rather than with solar wind or micrometeoroid fluxes .
Thermal Stability of Surface Minerals
The wide temperature excursions on Mercury’s surface can affect the stability of minerals. For example, oldhamite (CaS), a mineral thought to be present on Mercury, remains stable up to 723 K, which covers the highest recorded surface temperatures on the planet .
Conclusion
Mercury’s surface temperature varies dramatically, from below 100 K at night and in polar shadows to as high as 700 K at the equator during the day. These extreme conditions influence the planet’s surface properties, including mineral stability and reflectance, and allow for the presence of water ice in permanently shadowed polar regions. The unique temperature environment of Mercury is a direct result of its lack of atmosphere, slow rotation, and proximity to the Sun Bauch2021Hansen1974Chase1976+4 MORE.
Sources and full results
Most relevant research papers on this topic