What it was to become was uncertain until between 4.5 and 3.8 billion years when the dust settledinto a solid globe.when引导的这个从句是什么句子?

What it was to become was uncertain until between 4.5 and 3.8 billion years when the dust settledinto a solid globe.when引导的这个从句是什么句子?
What it was to become was uncertain until between 4.5 and 3.8 billion years when the dust settled
into a solid globe.
when引导的这个从句是什么句子?

What it was to become was uncertain until between 4.5 and 3.8 billion years when the dust settledinto a solid globe.when引导的这个从句是什么句子?
时间状语从句.
接在4.5 and 3.8 billion years 后,表示在这个时间尘埃落定后,一切明朗之类的.