Our colleague O. Groussin, from the Laboratoire d’Astrophysique de Marseille in France, has led a comprehensive analysis of the thermal environment of comet 67P by using high resolution shape models of its nucleus. This study, carried out as part of our ISSI team efforts, has just been accepted for publication in Astronomy and Astrophysics, and can be found in this link.
Image of 67P. Copyright: ESA/Rosetta/NAVCAM, CC BY-SA IGO 3.0
This study indicates that the thermal environment of comet 67P is heavily influenced by the large tilt of its spin axis (52°), which leads to significant seasonal changes and long polar nights. It is found that the northern hemisphere is the coldest, with temperatures ranging from 210–300 K, and water ice can be found near the surface, while CO2 would be located deeper. In this hemisphere, erosion occurs faster on cliffs than on plains, forming terraces. In the southern hemisphere, temperatures can rise to 350–400 K at perihelion but drop to 55 K during the 5-year polar night. In this region, CO2 accumulates near the surface during the polar night, enriching the area. Due to the intense perihelion heating, it is found that erosion is stronger in the southern hemisphere, contributing to its flatter appearance compared to the northern hemisphere. The study also reveals that self-heating and thermal conduction contribute significantly to the comet’s energy budget.
Featured image: Part of Fig 1 in Groussin et al (2025) showing the cumulative energy from self-heating.