A Slow-Motion Strobe Light

摘要

Mercury does not have a traditional atmosphere in the sense of a thick blanket of air, but it does have an exosphere: an "atmosphere" so tenuous that atoms can bounce across the surface like billiard balls without colliding with one another. The atoms come from the surface via several processes. Sunlight knocks them out of mineral crystals and evaporates volatile elements such as sodium; ions from the solar wind bombard minerals and eject atoms from them; and the steady hail of micrometeoroids vaporizes surface materials.