Navigation

avigation is the steering or directing of a course. Migrating birds, animals, and even insects seem able to navigate across the world with ease. People have developed ways of using nature, science, and technology to do the same thing—to figure out their position and find their way across land, sea, sky, and even in space.

Following Instinct and Landmarks

Monarch butterflies fly more than 1,500 miles (2,400 kilometers) on their annual migration across North America. One seabird, the Arctic tern, makes the longest migration journeys of any living creature. Every year, it flies up to 22,000 miles (35,400 kilometers) between the Arctic and Antarctic. Some animals are born with an instinct for migrating in a particular direction. Birds may navigate by recognizing familiar landmarks such as rivers and mountains. They also may use the position of the Sun and stars. Yet others seem to be able to sense the Earth’s magnetism, as if they have a nat­ural compass that directs them.

The first pilots relied on navigation methods similar to those used by birds. Planes flew low so that pilots could nav­igate visually by following landmarks such as roads, rivers, and railroads. For longer flights and for flights over oceans, a method called dead reckoning was used. A pilot used a map to figure out which direction to fly and then

measured the distance to the destination. Knowing how fast a plane flew, a pilot could figure out the journey time. If the plane was flown in the right direction (using a compass) at the correct average speed for the calculated length of time, it should arrive at its destination. In the real world however, an aircraft could be blown off course by wind, so pilots had to allow for this when plotting their course. Today, pilots of small aircraft still can navigate using dead reckoning and by looking out for landmarks.

THE STARDUST MYSTERY,

In 1947, an airliner called Stardust was flying from Buenos Aires, Argentina, across the Andes moun­tain range to Santiago, Chile. Just before it was due to land, it van­ished. Searchers found nothing. In 2000, the wreckage was found, and an explanation to the old mystery was pieced together. Because of bad weather, the airliner had flown so high that it reached the high-speed air current of the jet stream and was flying against it. The crew’s naviga­tion calculations indicated that they had crossed the mountains, but the jet stream had slowed them down so much that they were still over the mountains. Thick clouds prevented them from seeing the ground. As they descended to land, the plane crashed into a mountainside and fell onto a glacier, a slow-moving river of ice. The wreck was soon covered with snow and then sank into the glacier. It took fifty-three years for the wreckage to travel downhill inside the glacier and appear at the bottom.

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