Engines of Our Ingenuity

No. 290:
MAPPING THE MOON

by John H. Lienhard

Click here for audio of Episode 290.

Today, we map the moon. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Mapping the moon became a matter of widespread fascination right after it'd been viewed through the first telescopes in 1609. Galileo made the first really good drawings of the moon -- a set of beautiful sepia renderings of the moon in its several phases. They could be called maps. He even made topographical estimates based on the length of shadows.

The telescope improved rapidly. By 1747 Johannes Hevelius of Danzig had produced a fine map. It not only showed all the major features, but it also took account of something many of us may not realize today: although the moon is in synchronous rotation with the earth, and it shows us only one side, its axis of rotation doesn't stay parallel with ours. We get to see just a little bit over the top and under the bottom. We actually get to see 59 percent of the moon's surface from Earth.

Four years after Hevelius, a Jesuit named Riccioli made a lunar map and assigned many of the names we use today. He accepted the idea that the dark regions of the surface might be oceans. He gave us those wonderful names: Sea of Tranquility, Sea of Serenity, Sea of Fertility, and Ocean of Storms. He also continued the earlier practice of naming craters after scholars.

In 1665 Robert Hooke finally realized that the seas weren't seas at all. They were sandy regions that reflected less light. Hooke reduced the moon to no more than desolate earth. For the next three hundred years, improvements of lunar mapping followed improvements of telescopes and mathematical methods. Only that unseen 41 percent of the surface lingered to tease the human imagination. And tease us it did, until we finally saw pictures of the far side of the moon in October, 1959. They were given us by an unmanned Russian satellite only two years after Sputnik.

Lunar mapping was stepped up enormously in the mid 1960s in preparation for moon landings. But surely the most dramatic moment in the whole enterprise was in December, 1968: Astronaut Frank Borman rode his orbiter around the far side of the moon -- the first living creature to gaze at that surface. It was Christmas Eve when he read to us from Genesis: "In the beginning God created the heaven and the earth."

Suddenly, the magnitude of this human accomplishment was clear. Suddenly we saw the moon whole. A few months later Neil Armstrong actually set foot on the moon and, by the oddest twist of human psychology, we were once again reduced to mere ants crawling about a surface.

Today we know the moon too well. The age-old mysteries have been removed. Today we have to look to Mars -- and, I suppose, to Andromeda.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)


Wilford, J.N., The Mapmakers. New York: Vintage Books, 1982, Chapter 23.

The Galileo sketches of the moon may be seen at: http://galileo.rice.edu/sci/observations/moon.html


The Engines of Our Ingenuity is Copyright © 1988-1997 by John H. Lienhard.


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