Mooning

Far greater than the sum (10,000 francs, or about $390) is the honor attached to the annual R. E. P.-Hirsch prize of the French Astronomical Society. Far greater than the practical effect was the imaginative content of the work for which a young German named Oberth, experimenting in Rumania, last week received this year's Hirsch award.

Getting to the moon was the object of Herr Oberth's researches. The Society considered that he had actually made progress toward ''practical interstellar navigation." The problem begins, and so far has ended, with the forces by which Earth clutches that which is its own. To escape the pull of gravity, an earthborn body would have to take off at terrific speed. Outside the earthly atmosphere, interstellar gases are so rare that they would afford no traction for an airplane's propellor, no buoyance for wings. Most scientists with lunar leanings have therefore pondered shooting themselves moonwards in rockets. Herr Oberth, bearing in mind the desirability of returning and landing on the earth, cogitated combining plane and rocket, using the latter for propulsion of the former as has been done experimentally at the Opel works in Germany. The core of his cogitations concerned the materials to be fused to attain speed in and out of Earth's atmosphere. He described two kinds of fuses--one using hydrogen, the other of alcohol--which he calculated would drive a plane 13,120 ft. per sec., or about 9,000 m. p. h., making the 240,000-mile trip in some 27 hours.

After praising Herr Oberth and giving him the prize, the French Astronomical Society gravely warned that trips to the moon are still wholly impractical.

What sunrise is like on the moon can now be demonstrated as well as described. Edward G. F. Arnott, student at Princeton's Graduate School, got his engineer-father to rig an ordinary amateur cinema camera at the small end of Princeton's 23-inch telescope. They slowed down the camera's action 100 times, since a lunar day passes 9/1000 as fast as an earthly one, and took a picture of how dawn comes to Copernicus, one of the moon's biggest pits. Because the moon has no atmosphere, there is little or no crepuscular glow. The sun ''rises" abruptly, deep black shadows retreating sharply before it. In the Arnott film, shown last week by Princeton Professor John Stewart, the silver edge of a lunar morning creeps up the steep walls of the volcano, two miles high. Long shadows of the craggy rim are cast across the crater floor within, slowly shortening until all is day.