Venus Observed

Venus is the earth's nearest planetary neighbor (minimum distance: 26 million miles), but the dense white clouds that fill her atmosphere make her more mysterious than many a far-distant star. In Nature, Radioastronomer JohnD. Kraus of Ohio State University tells how he has added, he hopes, one new fact to the few known about Venus.

Since early spring Dr. Kraus has received irregular bursts of 11-meter radio waves from Venus. Every day he measured a rough peak of radio activity, and the peaks came earlier each day by a little less than two hours. After diagraming the peaks, Dr. Kraus concluded that Venus revolves on its axis in about 22 hrs. 17 min.

The periodic radio signals, he thinks, come from "sources" that are clustered predominantly on one side of the planet. The radio waves from the sources are normally reflected back to the planet's surface by ionized layers in the Venusian atmosphere. The only waves that reach outer space are those that travel vertically and are therefore reflected less strongly. In effect, a broad beam of radio waves sweeps around Venus as the planet revolves. Only when the beam points toward the earth is it detected by Dr. Kraus. So the time between the peaks of energy gives Venus' period of rotation.

Dr. Kraus does not claim to know what the mysterious sources may be. He suspects that they are thunderstorms. He has no idea why they seem to be concentrated on one side of the planet. When the reason for this lopsidedness (a continent? ocean? mountains?) has been deduced, it will be the first information gathered by man about the Venusian surface.

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