THE
MOON: A NICE PLACE TO VISIT?
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.
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