mascon

mas.con

n.（名词）
A mare on the moon having rock of greater density than that of the surrounding area, thus exerting a slightly higher gravitational force.
质量密集：月球上的阴暗部，其内部岩石比周围地区的岩石的密度大，因此产生略大些的引力

来源：
mas(s)
mas(s)
con(centration)
con(centration)