THE MOON: A NICE PLACE TO VISIT?

THE MOON: A NICE PLACE TO VISIT?

  

Read the passage.

 

           The moon has been described by songwriters and poets as a place for a romantic escape. We know of course that the moon is actually a very hostile environment for human beings.

          The moon is completely devoid of water because the force of gravity on the moon is much less than on the earth. (The moon is much smaller; its surface is about as large as Africa.) The lack of a strong gravitational pull has caused any water the moon may have had to leak out into space over the 4.6 billion years that it has been in existence. Of course, since there is no water, there is also no vegetation. So if you go, bring your lunch.

          There is no air on the moon because its gravity is insufficient to retain an atmosphere. Accordingly, travelers to the moon require not only oxygen and water but also protection against cosmic rays that are unfiltered by an atmosphere. No atmosphere also means no weather - no wind, no rain, no cloud.

          Temperatures on the moon are quite extreme, ranging from 110°C to –173°C. This occurs because there is no atmosphere to filter the sun's rays when it is shining and then to blanket in warm air when the sun goes down. These extremes of temperature are particularly striking during a solar eclipse, when the earth passes directly between the sun and the moon, temporarily blotting out the sun's light.  At such times the temperature on the moon dips very rapidly and then rises immediately as the sun emerges from the earth's shadow. The change in temperature may be as much as 200°C in one hour! This sudden change can cause rocks to shatter due to the alternate expanding and contracting. Thus if you visit the moon, deciding what to wear could be a problem.

          There is no twilight or dawn on the moon. Like the earth, the moon does not shine by its own light; it reflects the light of sun. Unlike the earth, however, there is no atmosphere to diffuse the light as day becomes night and night turns into day. Changes from light to dark and dark to light occur suddenly.

The lunar sky is black.  (Blue sky on the earth is produced by the scattering of blue light in the spectrum by particles of air.)  On the moon stars are visible in the daytime, but you would have to shield your eyes from the unfiltered sunlight to view them.

          There is no sound on the moon. Sound travels on waves of air molecules.  Since there is no air, there is nothing to transmit sound. Leave your transistor home. Also, the moon is not a magnet the way the earth is. You can leave your compass home too.

          The moon is a satellite of the earth, revolving around the earth once every twenty-nine and a half days. The moon itself rotates, but it does so very slowly. Therefore the same side of the moon is always visible to us. To get to the moon, you would have to travel 240,000 miles, a distance that is about the same as circling the earth at the equator ten times.

          It is clear that if you were making a trip to the moon, you should need to pack more than a toothbrush and a change of underwear. Its adverse conditions would make it very difficult for a visitor from the earth.