原げん始し惑わく星せい

noun

protoplanet

Astronomical term for a planet in its early formation stage, before it has cleared its orbit or fully differentiated.

• 原げん始し惑わく星せい系けい円えん盤ばんの中なかで、微び惑わく星せいが衝しょう突とつ合がっ体たいして原げん始し惑わく星せいが形けい成せいされる。

  In a protoplanetary disk, planetesimals collide and merge to form protoplanets.