A. How the seafaring skills of Polynesians resembled those of the Vikings
B. How Pacific Islanders were able to navigate without instruments
C. How the patterns of stars differ to the north and south of the equator
D. How navigational instruments developed over time
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NARRATOR:Listen to part of a lecture in an astronomy class.
MALE PROFESSOR: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 peoples 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.
Um, the key to the pacific islanders' success was probably their location near the equator.What that meant was that the sky could be partitioned, divided up, much more symmetrically than it could farther away from the equator. Unlike the Vikings, early observers of the stars in Polynesia, or really, anywhere along the equator, would feel that they were at the very center of things, with the skies to the north and the skies to the south behaving identically; they could see stars going straight up in the east and straight down in the west.So it was easier to discern the order in the sky than farther north, or farther south, where everything would seem more chaotic.
Take the case of the Gilbert Islands, they are part of Polynesia, and lie very close to the equator. And the people there were able to divide the sky into symmetrical boxes, according to the main directions—north, east, south and west.And they could precisely describe the location of a star by indicating its position in one of those imaginary boxes.And they realized that you had to know the stars in order to navigate; in fact, there was only one word for both in the Gilbert Islands; when you wanted a star expert, you asked for a navigator.
Um, islanders from all over the pacific learned to use the stars for navigation, and they passed this knowledge down from generation to generation.Some of them utilized stone structures called “stone canoes.” ah, and these “canoes” were on land, of course, and you can still see them on some islands today.They were positioned as if they were heading in the direction of the points on the sea horizon where certain stars would appear and disappear during the night.And, um, young would-be navigators set by the stones at night and turned in different directions to memorize the constellations they saw, so they could recognize them and navigate... by them later on when they went out to sea.
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.
旁白：请听一段天文学课上的演讲。
教授：好的，上次我们谈到古代农业文明，说到古人通过观察星象，利用观察结果来追踪季节变化。但是今天我要讲的是星象对于早期船员的重要性，关于怎么利用固定的星象模式作为协助航海的工具的。
好的，你们都已经听过北欧海盗和他们让人钦佩的航海技术了，但是太平洋岛出海的人，即波利尼西亚人和密克罗尼西亚人，他们可能是世界上最为伟大的航海名族了。远在在欧洲先进的航海工具被开发出来之前，太平洋岛上的居民就已在新西兰到夏威夷之间穿梭，没有借助任何工具，就靠行星来导航。
嗯，太平洋岛上的居民成功导航的关键很可能在于他们所处的位置靠近赤道。这就意味着这里天空可能被分隔开来，比起远离赤道的地方，这里被分割开来后更显对称。不像北欧海盗，早期在波利尼西亚或其他沿着赤道观察星象的人会觉得，他们就在地球的中间地带，北边的和南边的天空的现象相同。他们可以看到星星在东边直线上升，西边直线下降。因此，这里更容易看出星星的移动顺序，而在赤道以北以南，什么似乎都杂乱五章。
就拿吉尔伯特群岛来说，它们是波利尼西亚的一部分，地处赤道附近。根据主要方位东南西北，那里的人们可以将天空分成对称的区域。他们可以通过指出星星在这些想象区域里面的位置，从而来精确地描述星星所处的方位。他们意识到必须了解星星才能航行。事实上，在吉尔伯特群岛上，人们有一句话。当你缺少一位行星专家，你需要的是一位航海员。
嗯，遍布太平洋岛上居民都学会了怎么使用行星来导航，这种技巧代代相传。某些人还利用石头结构，叫做石制扁舟，额，这些船都放在陆地上，当然，现在你还能在某些海岛上看到。这些船所处的位置就好像他们正朝着海平面的方向前进，在那里晚上会有某些星星出现又消失。年轻的预备航海员晚上便会将船移向不同方向以记住他们看到的星座，这样他们便可认出方向出海导航。
波利尼西亚人定位自己的一种重要的方法便是利用天顶星导航。天顶星是一颗很亮的星星，它会在某一特定纬度直接从头上经过。在与赤道的特定距离上，纬度经常和某一太平洋岛屿相近。因此，波利尼人可以通过观察某个天顶星是否在夜间直接从头顶飞过，从而估算出他们的纬度。他们会知道，他们是否达到了他们想要到达的特定岛屿的纬度。波利尼西亚人使用的另一种技巧是通过观察星对。这指的是两颗同时升空的星星，或是同时出现。导航员可以把这些星对当做参考点，因为它们只在特定的纬度升起或聚集在一起。所以导航员可能看到一对星对一起出现，而，呃，他们便知道了自己离赤道北边或南边多远。而如果他们继续前行，第二天晚上他们就会看到星对分开来的情景，他们便知道自己处在不同的纬度上。所以观察上升或出现的星对来导航是一个不错的技巧。嗯，事实上，行星所处的位置更有意义，他们只要看着就可以了，而不用猜测他们何时会升起。
嗯，好的，我想所有这些显示了导航真的不需要多么花哨的导航工具。太平洋岛屿上的居民就有这样专业的天文学知识和导航技术，这使得他们能够在广阔的海洋上自由航行。额，甚至有可能的是，波利尼西亚导航员早在哥伦比亚发现新大陆几个世纪前就到过美洲大陆。
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