The Thermal Equator on Earth and Mars

Abstract The thermal equator (also known as the heat equator) is the circumplanetary set of points that represent the highest mean annual temperature at each longitude. Recent high precision global datasets for Earth and Mars provide a basis for a detailed calculation of the thermal equator on these worlds. On Earth, the temperature values that comprise the thermal equator range from 25.85° to 34.75°C, with a mean of 27.75° ± 1.3°C, and extends in latitude as high as 20°N in Mexico and 29.3°N in the Indian subcontinent. The maximum southern extent is 20°S in Australia. On Mars, lacking oceans, the thermal equator takes a simpler track and is roughly parallel to the equator, and displaced 5°–10°S. However, there is a region of longitude on Mars where the thermal equator becomes bimodal with a northern branch centered at 10°N and a southern branch centered at 20°S.