Northern Lights

Man's explanations of the aurora borealis over the centuries have been as colorful as the spectacle itself. When great luminous curtains seemed to swish and crackle in the sky, Norsemen knew that Valkyries were riding abroad. Midwestern Indians looked up and thought they saw the fires of northern medicine men making stew of their enemies. Today's Eskimos watch the polar pyrotechnics and mumble about the spirits of the dead. Modern science has still another theory.

Millions of miles away in space, says Harvard's Astronomer Donald H. Menzel, the sun revolves like a tremendous lawn sprinkler. From its seething corona dense clouds of hydrogen squirt out at speeds up to 600 miles a second. Every so often one of those clouds hits the earth and bathes the planet in a shower of solar gas. But earthlings are protected by bumpers of magnetic force--invisible bars that stretch from pole to pole.

Heavy enough hydrogen clouds, however, manage to bend the magnetic lines of force into a gigantic funnel. Then sun particles pour through into the earth's atmosphere. Oxygen atoms near the earth's surface begin to glow and sparkle when struck by the speeding hydrogen. All through the "magnetic funnel" the luminous oxygen shimmers and shines in crimson and yellow and green streamers, which are the waving rainbow of the northern lights.

Much of the world's weather is manufactured in those frigid air masses where the aurora brightens the long polar nights. Dr. Menzel believes that as much energy goes into the display as the earth normally absorbs from the heat and light of a day in the sun. If further observations prove him correct, even meteorologists in latitudes far from the pole will be checking on the faraway fireworks of the aurora borealis before they make their forecasts.

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