Orbital eccentricity driven temperature variation at Mercury's poles

Abstract

AbstractDue to Mercury's extremely small obliquity, variations in orbital eccentricity are likely to have been the dominant cause of changes in polar temperatures on Mercury throughout the bulk of its history. In the last 10 Myr, the eccentricity has varied between 0.1 and 0.3. Over the past 100 Myr, eccentricity extremes of nearly zero to greater than 0.4 have likely been reached. We calculate the temperature in the near‐polar region (within 10° of the North Pole) as it varies in response to past eccentricities. These calculations show periods with dramatically different temperatures, diurnal amplitudes, and long period thermal cycles—all of which can have a dramatic effect on longitudinal variations in long‐term subsurface ice stability. Given forthcoming topographic data, thermal models including long‐term eccentricity can help constrain when past ice might have been delivered to Mercury.