Tommy Holahan, age 9, of Visalia, California, for his question:
How can the dead moon shine?
We all have seen those new close up pictures of the moon. The ground there looks a lot like a bare patch of rocky ground on the earth. With this in mind, it is natural for a thoughtful young person to wonder how the drab moon can shine with such golden glory.
The Full Moon glows like a golden lantern, and everybody knows that the flame inside a lantern must be lit to make it glow. But scientists have been saying for ages that the moon has no light of its own. As last the space age has given us photographs of the lunar landscape. .Now we all know for sure that it really is nothing more than a bare stretch of gritty ground, punctured with hollows and strewn with bumpy rocks. The moon has no light of its own to shed, no big, candle, no flame to make it glow. Nevertheless, we also know for sure that the moon does shine and shed its golden light upon the earth.
You can understand this puzzle if you wait fox dark and try a few tricks with an ordinary flashlight. Choose a dark wall and aim your flashlight to shed a beam of light upon it. The beam makes a circle of light, a yellowing circle that is paler and brighter than the rest of the dark wall. What you see, of course, is light from your flashlight, but it has gone through a few tricks before reaching your eye.
The light travels in a straight line from your flashlight, fanning out as it goes. When it strikes the solid wall, some of its beams bounce back and travel in the opposite direction, fanning out as they go. Some of these returning beams reach your eyes and bring you a picture of the lighted circle upon the wall. This trick of light is called reflection. You know that the dark solid wall has no light of its own to make a bright yellow circle. The circle shines with light borrowed from the flashlight beam. The moon also shines with reflected light and by now you can guess where it gets the light it borrows.
The light that shines down on the drab, rocky face of the moon of
course comes from the radiant sun. And the sun is a seething nuclear furnace, millions and millions oftimes more dazzling than a weak little man made flashlight. The sunbeams that strike down on the face of the earth are first filtered by the atmosphere above our heads. The moon has no airy atmosphere and the direct rays of the sun fall straight onto its face. Some of those sunbeams bounce back and reflect out into space. The moonlight we see comes from reflected sunshine.
The blazing sun lights the moon and the moon sends some of its sunshine along to us. It sends us about seven of every 100 sunbeams it gets.
The moon of course is a round ball and the sun lights only one side at a time. Some¬times we can see the whole daylight side. This is the golden circle of the Full Moon. When only half of the daylight is on the side facing earth, we see the golden Half Moon. When most of the moon's daylight is on the far side of the moon, «e see only a Quarter Moon, a slim golden crescent peeping around one side.