Why do astronomers think that there may be other advanced civilizations?

What was istanbul called before he ottomans conquered the city in the 15th century

Impressions of tropical swamp plants were observed on rocks in polar regions. the impressions were dark black imprints, which means the fossils are examples of ( 1 ) the fossils tell us that polar regions ( 2 ) ( 1 ) a. carbonization b. mineralization c. trace fossils ( 2 ) a. had tropical plants that can grow in ice b. might have had a diffierent climate in the past c. will have abundent vegitation

Which modern technology has not made a great difference in the inuit way of life?