noun🔗Share原行星，行星胚胎。 An astronomical object, approximately the size of the Moon, formed from the mutual gravitational attraction of planetesimals; they are thought to collide with each other and slowly form planets"Scientists believe that protoplanets, formed from smaller space rocks, eventually crashed together to create the planets in our solar system. "科学家们认为，**原行星（行星胚胎）**是由较小的太空岩石相互吸引形成的，最终它们相互碰撞，形成了我们太阳系中的行星。astronomyspacescienceChat with AIVocabulary GamePractice Reading
