Maps take flight

Natural History, Oct, 2005 by Robert Anderson

Recently I read Fatal Passage, Ken McGoogan s 2002 biography of a remarkable yet largely forgotten Arctic explorer, John Rae. Traveling by dogsled, in the style of the Inuit, Rae trekked thousands of miles along the northern coast of North America to fill in the blanks on regional maps. On May 6, 1854, from atop a barren ridge, he charted a strait that now bears his name, the final link in the long-sought Northwest Passage.

Like countless explorers before him, Rae always sought the high ground, the better to observe the surrounding terrain. Later cartographers sought the vantage points afforded by balloons, airplanes, and satellites to trace the lines of lands and seas on Earth. Decades have now passed since all the blanks were filled in. Could the glory days of mapmaking have already come to an end?

To judge from some of the tools and information recently available on the Web, the glory days are just beginning. A few months ago Google launched its ambitious new "Google Earth," billed as a "3D interface to the planet" (earth. google.com). You'll need to download Google's free software to use it (it works with computers running Windows 2000 or later, but, at the time of this writing, Macintosh users are out of luck). Enter a street address, at least in the United States, Canada, and the U.K., and you will zoom seamlessly from an Apollo 8-like vantage point to right above the rooftops. You can then tilt and rotate the view and soar over the landscape like a bird. You can even exaggerate the vertical relief of the simulated landscape by a factor of three.

If your system won't run Google Earth, the company has another mapping site (maps.google.com) that does much the same thing, but without the ability to "fly" over the landscape or tilt your flight perspective. I entered my street address, but the Web site flagged my next-door neighbor's house by mistake. Nothing's perfect.

The National Atlas of the United States of America (www.national atlas.gov) is another remarkable resource for exploring the U.S. through maps and images. Updated quarterly by the U.S. Geological Survey (USGS), it combines data on people, infrastructure, and natural resources culled from twenty government agencies. Visitors can create maps tailored to their needs by clicking on "Map Maker," but I preferred the site's "Dynamic," or interactive, maps. I found the "Tapestry of Time and Terrain" was my favorite, with its overview of our nation's geology.

For much of the twentieth century the best views of the terrain in the U.S. were the USGS'S topographic maps. For many purposes, such maps are more practical than satellite images. You can find them for free on the Internet at the National Atlas or at topozone.com.

During an eleven-day mission in February 2000, the Space Shuttle Endeavour used radar to generate a new topographic database of our planet. NASA promises to release the finished product to the public by this December. Go to www2.jpl.nasa.gov/srtm/for more on the "mission to map the world."

For live-feed, up-to-the-minute views from a satellite-borne webcam, see the "Earth and Moon Viewer" (www. fourmilab.ch/earthview/vplanet.html), by software writer John Walker. I particularly like the feature that helps me comprehend global time. Select a location from "various cities" and then hit the "hemisphere" view under the resulting map. From a million kilometers above, you can see the regions of the planet illuminated by the Sun at any given moment. At noon this time of year, I can see Rae's Strait, near the edge of darkness.

ROBERT ANDERSON is a freelance science writer living in Los Angeles.