Science on the Moon
Section 2.3.
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What We Don't Know About the Moon

One of the major activities of lunar colonists will be exploring the moon to uncover its mysteries.

"What mysteries," you ask. "Didn't we learn everything there is to know about the moon from Apollo?"

Nope, not even close. We learned a heck of a lot that we didn't know, but Apollo and the robotic moon probes barely scratched the surface (literally!) of the moon. To further that thesis, I offer:

What We Don't Know About the Moon
Episode 1: The Mystery of Linné Crater

The next time you have your binoculars pointed at the moon, scan over toward the Sea of Serenity, Mare Serenitatis. You'll see a large, white structure sitting pretty much by itself over toward the western edge, about the middle of the Sea measured from north to south. That's Linné crater.

Linné crater is named for a Swedish botanist, Karl von Linné. His claim to fame is that he invented the system of classifying plants and animals. If you study botany, you might have heard of him by his Latinized name, Carolus Linnaeus. That's because back in the 1700s, folks liked to write papers in Latin -- it was the lingua franca of the scientific world. The United States of America was still struggling for its independence from England when Linné died in 1778. He never had much to do with exploring the moon, but his name is preserved because about fifty years after his death, J. H. von Madler published a map of the moon on which, in 1837, he named this interesting crater after Karl von Linné.

A few years before that, in 1824, Wilhelm Gotthelf Lohrmann published his Lunar Map in Twenty-Five Sections. The same crater appears on Lohrmann's map, identified only as "crater A." This crater seemed to have considerable fascination for moon mappers, perhaps because it was easily recognizable in their telescopes as it stood in isolation in the Sea of Serenity surrounded only by a few low ridges.

Between 1841 and 1843, Julius Schmidt made several drawings of the crater. But then, in 1866, Schmidt noticed that the crater was gone! It had been replaced by a whitish region about six miles in diameter. He discovered a small mountain in the center of the white spot.

Just a month after Schmidt's announcement, Father Angelo Secchi of Rome figured out that the mountain was really a small crater about a half mile across. Then, using a more powerful telescope (the 10.5-inch instrument in Copenhagen), Ludwig d'Arrest measured the crater to be 1.5 miles in diameter.

Back then, astronomers concluded that they had seen the result of a volcanic eruption on the moon. They figured the crater seen by Lohrmann and von Madler must have been a dormant volcano which came to life between 1843 and 1866, covering the area with white ash. For years astronomers hoped to see more volcanic activity on the moon, but no one ever observed any. There's not much credit given to the volcano theory these days -- the moon appears to be just about as cold and dead as it can get -- but the mystery continues to this day. Some selenologists argue that Schmidt, et al, simply made mistakes in their observations, and that no change really took place; but it's unlikely so many observers would have made the same mistake. Today, the area still appears as a white region in western section of Mare Serenitatis.

How can we know what really happened at Linné crater?

There's only one way to find out: go there and look.

Science on the Moon

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