Question

finding the invisible
all over the planet, ancient tombs and temples lie hidden from view. so how do
archaeologists know where to begin digging? thanks to satellites, that question is
becoming easier to answer. in the pioneering field of satellite archaeology, satellites four
hundred miles above earth can identify structures buried under soil, covered by modern
construction, or obscured by forests. for example, mud bricks used by ancient egyptians
are more dense than soil, and the differences are detected by the satellites. advanced
computer programs map buried settlements and distinguish them from water, vegetation,
and farmland. sarah parcak, a pioneer in the field, says of the technology, \it allows you
to literally strip away vegetation and see entire cities beneath the rain forest canopy. this
is the unbelievable future of archaeology.\
what is the main, or central, idea of the passage?
satellite archaeology is a rapidly expanding new scientific field.
archaeologists are uncovering ancient hidden structures by using satellite
imagery.
archaeologists must determine where ancient structures are buried before
they can begin excavating them.

Explanation:

The passage focuses on how satellites help archaeologists locate hidden ancient structures, with examples of how satellite technology detects buried sites and expert commentary on its use. The first option only mentions the field expanding, not the core function. The third option only addresses the need to find sites, not the satellite solution. The second option captures the central action: archaeologists using satellite imagery to uncover hidden ancient structures.

Answer:

Archaeologists are uncovering ancient hidden structures by using satellite imagery.