Because the only source of heat that could melt the entire moon would be a very rapid accumulation of small bodies , the presence of large quantities of anorthosite in the lunar crust supports the theory that the moon coalesced from the debris of a planetary collision 能熔化整个月球的唯一热源是小型天体的快速聚集,因此月球地壳内大量的斜长岩支持了月球是由行星际遗屑撞击合并而成的理论。