基本解释星子假说同根派生 planetesimal hypothesis相关词英英字典柯林斯英英字典 the discredited theory that the close passage of a star to the sun caused many small bodies (planetesimals) to be drawn from the sun, eventually coalescing to form the planets planetesimal hypothesis剑桥字典planetesimal hypothesis柯林斯字典专业释义地球科学星子假说