civilization n. 文明
seafarer n. 船员
Viking n. 维京人
navigation n. 导航，航行
Polynesian n. 波利尼西亚人
Equator n. 赤道
zenith n. 天顶（太阳或月亮在天空中的最高点）
Columbus n. 哥伦布
Listen to the following recording and answer questions 1-3.
1) A. How the seafaring skills of Polynesians resembled those of the Vikings.
B. How Pacific Islanders were able to navigate with the aid of stars.
C. How the patterns of stars differ to the north and south of the equator.
D. How navigational instruments developed over time.
2) A. Both could help identify a location relative to the equator.
B. Both seem to have been used to determine the positioning of stone canoes.
C. Both were first developed by the Vikings.
D. Both were used as calendars to help keep track of the seasons.
3) A. strong body and determination
B. advanced navigational tools
C. the ability to keep track of the seasons
D. expert knowledge of astronomy as well as navigation
OK, last time we talked about ancient agricultural civilizations that observed the stars and then used those observations to keep track of the seasons. But today I want to talk about the importance of stars for early seafarers, about how the fixed patterns of stars were used as navigational aids.
OK, you've all heard about the Vikings and their impressive navigation skills, but the seafaring people of the pacific islands, the Polynesians and the Micronesians, were quite possibly the world's greatest navigators. Long before the development of, uh, advanced navigational tools in Europe, pacific islanders were travelling from New Zealand to Hawaii and back again, using nothing but the stars as their navigational instruments.
One important way the Polynesians had for orienting themselves was by using zenith stars. A zenith star was a really bright star that would pass directly overhead at particular latitude…at a particular distance from the equator, often at a latitude associate with some particular pacific island. So the Polynesians could estimate their latitude just by looking straight up, by observing whether a certain zenith star passed directly overhead at night, they'd know if they have reached the same latitude as a particular island they were trying to get to.
Um, another technique used by the Polynesians was to look for a star pair, that's two stars that rise at the same time, or set at the same time, and navigators could use these pairs of stars as reference points, because they rise or set together only at specific latitudes. So navigators might see one star pair setting together. And, uh…would know how far north or south of the equator they were.
And if they kept on going, and the next night they saw the pairs of stars setting separately, then they would know that they were at a different degree of latitude. So looking at rising and setting star pairs is a good technique. Um… actually it makes more sense with setting stars; they can be watched instead of trying to guess when they'll rise.
Uh, OK, I think all this shows that navigating doesn't really require fancy navigational instruments; the peoples of the pacific islands had such expert knowledge of astronomy as well as navigation that they were able to navigate over vast stretches of Open Ocean. Uh, it's even possible that Polynesian navigators had already sailed to the Americas, centuries before Columbus.
1. What does the professor mainly discuss?
2. What did the technique using zenith stars have in common with the technique using star pairs?
3. According to the professor, what made the pacific islanders able to navigate over vast stretches of Open Ocean?