Thermal illumination dating
During parts of a Mercury year, the radiation pressure from the scattering process is sufficiently strong to strip much of the atmosphere and form a long glowing tail.
Someone standing on Mercury’s nightside at the right time of year would see a faint orange similar to a city sky illuminated by sodium streetlights.
Scattered sunlight gives sodium a bright orange glow, which was observed by the Mercury Atmospheric and Surface Composition Spectrometer to vary seasonally with Mercury’s distance from the Sun.
The image shows topographic heights as measured by the Mercury Laser Altimeter and surface features mapped by the Mercury Dual Imaging System.Observations by MESSENGER’s Magnetometer showed that Mercury’s magnetic field is offset along the planetary spin axis by about 20% of the planet’s radius.The internal magnetic field is 100 times weaker than that of Earth and barely stands off the solar wind at the subsolar point to form the magnetosphere.The interaction of the planetary field with the solar wind generates currents in the magnetosphere, which induce external magnetic fields with magnitudes similar to or larger than the planetary field in much of the magnetosphere.
Hollows are shallow, irregular depressions and are a geologic landform discovered by MESSENGER that appears to be unique to Mercury.
The temperatures range from 50 K (purple) to 550 K (red).