Jonny Adams, age 10, of Claremore., Okla.,
What makes the moon reflect light?
Take a flashlight outdoors on some pitch black night. Switch it on and turn its yellow beam to light up a patch of the ground. The beam of light leaves the flashlight and fans out until it reaches the solid soil. There some of it is absorbed and the rest is reflected back for your eyes to see. Now turn the beam onto a surface of smooth water, a puddle or a pail of water. The lighted circle is brighter than the circle which reflects back from the rough dark soil.
This is because a smooth, pale surface reflects back more light than a rough, dark surface. This holds true for the soil and rocks, for the clouds and oceans all over‑the ‑surface of our planet. It also holds true '"'' for the surface of faraway planets, moons and asteroids. This reflection power is called albedo. Astronomers can tell a lot about the surface of a moon or planet from its albedo. The pale, dense clouds over Venus reflect back more than half the sunlight that strikes them. The rusty deserts of Mars reflect back only 15 per cent of the suns beams.
Our pale moon is but a ghost of the sun. We would need the light from about 169,000 full moons to equal the light from the summer sun. All these full moons would fill the whole sky several times. Even then, they would not give us the warmth of the sun. For the moon sends us little or none of the scorching sunshine that falls upon it.
The sun, of course, is a blazing nuclear furnace, pouring forth its radiant heat and light in all directions. Nothing else in the Solar System shines by its own light. We see the moon and planets, the comets and asteroids b y the reflected glory of the sun. These small heavenly bodies catch only a small fraction of the suns total output. The rest travels far out across space to wink at the distant stars.
The moon is very stingy with its sunlight. For its surface is made of dusty ashes and rough, dark rocks. Its surface absorbs more than 90 per cent of the light which falls upon it. If its surface were made of smooth, slippery ice, it would reflect ten times more light and the full moon would shine with a brilliant light.
As it is, the moon reflects only seven per cent of its sunlight. Its albedo is 0.07. This is very low when compared with pale, cloudy Venus. The albedo or reflecting power of Venus is 0.59 which is why Venus is sometimes the most brilliant planet in the sky.
The lunar day is two earth‑.weeks long and thb moon a1wahs facet 116 with the same side. Half the moon has daylight while the other half is in the shadows of night. The lunar day and night follow each other across our side of the moon, but we see only the area which is bathed in golden sunlight. This is why, during a lunar month, the moon seems to swell from a slim crescent to a golden pumpkin and then shrink to a sliver again.