Alan K. Henderson's Weblog


Old comments migrated to Disqus, currently working outtechnical issues

Monday, August 18, 2008

What Causes The Lunar Eclipse?

Two nights ago a partial lunar eclipse was visible South America, much of the Eastern Hemisphere, and a tiny sliver of North America:

The penumbral eclipse will begin at 18:23 UTC, with the partial eclipse beginning at 19:36. The time of greatest eclipse is 21:10. The partial eclipse will end at 22:44, and the penumbral eclipse will finally at 23:57.

This map shows the parts of the world where the eclipse coudl be seen.

Ever wondered what causes the lunar eclipse? The science is explained in Chapter 12 of Edgar Rice Burroughs' Jungle Tales of Tarzan. Tarzan speaks to Taug, one of the apes of his tribe about Goro (the apes' name for the Moon):

"Look, Taug!" exclaimed Tarzan, pointing toward the stars. "See the eyes of Numa and Sabor, of Sheeta and Dango [lion, lioness, panther and hyena - in the language of the apes]. They wait around Goro to leap in upon him for their kill. See the eyes and the nose and the mouth of Goro. And the light that shines upon his face is the light of the great fire he has built to frighten away Numa and Sabor and Dango and Sheeta.

"All about him are the eyes, Taug, you can see them! But they do not come very close to the fire--there are few eyes close to Goro. They fear the fire! It is the fire that saves Goro from Numa. Do you see them, Taug? Some night Numa will be very hungry and very angry--then he will leap over the thorn bushes which encircle Goro and we will have no more light after Kudu seeks his lair--the night will be black with the blackness that comes when Goro is lazy and sleeps late into the night, or when he wanders through the skies by day, forgetting the jungle and its people."

Taug looked stupidly at the heavens and then at Tarzan. A meteor fell, blazing a flaming way through the sky.

"Look!" cried Tarzan. "Goro has thrown a burning branch at Numa."

Numa would soon approach victory over his intended celestial prey:

One night when Taug lay sleepless looking up at the starry heavens he recalled the strange things that Tarzan once had suggested to him--that the bright spots were the eyes of the meat-eaters waiting in the dark of the jungle sky to leap upon Goro, the moon, and devour him. The more he thought about this matter the more perturbed he became.

And then a strange thing happened. Even as Taug looked at Goro, he saw a portion of one edge disappear, precisely as though something was gnawing upon it. Larger and larger became the hole in the side of Goro. With a scream, Taug leaped to his feet. His frenzied "Kreeg-ahs!" [warning cries of the apes] brought the terrified tribe screaming and chattering toward him.

"Look!" cried Taug, pointing at the moon. "Look! It is as Tarzan said. Numa has sprung through the fires and is devouring Goro...He is in danger and none can help him--none except Tarzan. Soon Goro will be devoured by Numa and we shall have no more light after Kudu [the sun] seeks his lair."

The apes watch the spectacle in horror:

And as the tribe waited they watched the slow devouring of the moon. Already Numa had eaten out a great semicircular piece. At that rate Goro would be entirely gone before Kudu came again. The apes trembled at the thought of perpetual darkness by night. They could not sleep. Restlessly they moved here and there among the branches of trees, watching Numa of the skies at his deadly feast, and listening for the coming of Taug with Tarzan.

Tarzan comes to save the day - er, night:

The ape-man wasted no time in idle words. In his hand was his long bow and at his back hung a quiver full of arrows, poisoned arrows that he had stolen from the village of the blacks; just as he had stolen the bow. Up into a great tree he clambered, higher and higher until he stood swaying upon a small limb which bent low beneath his weight. Here he had a clear and unobstructed view of the heavens. He saw Goro and the inroads which the hungry Numa had made into his shining surface.

Raising his face to the moon, Tarzan shrilled forth his hideous challenge. Faintly and from afar came the roar of an answering lion. The apes shivered. Numa of the skies had answered Tarzan.

Then the ape-man fitted an arrow to his bow, and drawing the shaft far back, aimed its point at the heart of Numa where he lay in the heavens devouring Goro. There was a loud twang as the released bolt shot into the dark heavens. Again and again did Tarzan of the Apes launch his arrows at Numa, and all the while the apes of the tribe of Kerchak huddled together in terror.

At last came a cry from Taug. "Look! Look!" he screamed. "Numa is killed. Tarzan has killed Numa. See! Goro is emerging from the belly of Numa," and, sure enough, the moon was gradually emerging from whatever had devoured her, whether it was Numa, the lion, or the shadow of the earth; but were you to try to convince an ape of the tribe of Kerchak that it was aught but Numa who so nearly devoured Goro that night, or that another than Tarzan preserved the brilliant god of their savage and mysterious rites from a frightful death, you would have difficulty--and a fight on your hands.

Labels: ,

Site Meter