In which sentence does an adverb clause modify an adverb?

Question

We used safety goggles when we viewed the eclipse.

A full lunar eclipse lasts longer than a partial eclipse.

The scientists studied the sun as the eclipse’s shadow swept across Earth.

When people did not understand the science behind an eclipse, they were afraid of the solar and lunar events.

Answer 1

In the sentence "The scientists studied the sun as the eclipse’s shadow swept across Earth," the adverb clause "as the eclipse’s shadow swept across Earth" modifies the adverb "studied," indicating when the scientists were studying the sun.