Evening star. [volume] (Washington, D.C.) 1854-1972, 1958-08-17
FACT AND FANTASY
FACT AND FANTASY
What We Already Know About the Moon
By WILLIAM HINES
star star Writer


star star Writer
Several years ago. in an airplane
bound for New York. the rocket
expert, Willy Ley, was discoursing
as he ALWAYS discourses best: TO an
audience Of one. He was PROFOUND
ing his thoughts about fight to
the moon.
I'm one respect, the first man
TO 60 to the moon will have 1t all
over Columbus" Mr.. Ley said.
"After all, when Columbus sailed,
he didn't know where he was 60
ing couldn't see his objective and
didn't know where he was when
he got there.
"A lot more is known about the
moon today than was known about
the earth in Columbus time"
This is true. No object in the
heavens and few on earth have
already been studied with the as
seriousness applied to the lunar
branch of astronomy. Its diameter
is known to an accuracy of a few
hundred feet; its mass has been
computed to within a matter of
tons: its movements have been
charted with incredible accuracy.
The Scientific Attitude
Scientists-who by the time
you read this article may already
have fred their first moonward
shot-are unconcerned about the
moon as something dogs bay to
and lovers pray to. They are
interested in it as one of the cog
wheels in that intriguing celestial
machine known as the solar
system
There are several theories about
the moons origin. The prevailing
scientific theory is that the moon.
along with all the planets and
most of the satellites of the solar
system, was formed by a cosmic
turbulence several billion years
ago. Pretty we'll abandoned is
the notion that the moon was
sucked up out of the Pacific Ocean
In some manner.
Under the prevailing theory, the
moon can be considered either
as a satellite of earth or as the
tenth major planet in the solar
system. Most astronomers regard
1t as satellite, but lean toward
the twin-planet view a bit when
they refer to the "Earth-Moon
system" as a single cosmic entity.
Some astronomers think the size
of the moon relative to the earth
makes it properly second planet.
1t is not enough to say the
moon is a satellite of earth be-
cause it revolves around the earth.
Actually, both the moon and the
earth revolve around common
center. That this center of mass
happens to be far down below the
surface of the earth has nothing
to do with the case; the earth's
center and the earth-moon sys-
TENS center are two quite diff
ferent points.
The Biggest Satellite
If the moon is a satellite, it is
by far the biggest in the solar
system in relation to its principal
Croughly one-fourth the earth's
diameter, one-eightieth its mass.
If it is a planet sharing the
earth's orbit, it is the solar Sys-
TENS smallest (about two-thirds
the diameter of Mercury.
The moon is not the solar syS-
TENS biggest satellite, however.
This distinction is shared by two
of the moons of the giant planet
Jupiter. Their names are Callisto
and Ganymede.
AS a planet, the moon has a
year identical to earth's, and like
earth, it's distance from the sun
is about 92.9 million miles, or
one astronomical unit. So much
for the planet moon"
AS a satellite, the moon has a
period of 27.32166 days relative
to the fixed" stars and 29.53059
days relative to the sun. There
are other kinds of lunar months,
but for the layman it is sufficient
to think of the moons month as
being 20 days long-roughly Is
lunar months to the year.
The moons diameter is 2,1599
miles and it's distance from the
earth (center to center Of the
two bodies, mind YOU'D varies be-
tween 221,463 miles and 252,710
miles, with the mean distance"
being reckoned at 238,860 miles.
Today, August IT, 1858, the
moons distance from the earth is
226,153 miles. Allowing from the
distances from centers to surfaces,
this means that the launching
pad at Cape Canaveral is about
221,140 miles from the nearest
point on the face of the moon.
This is very close to 100 times the
distance from Washington to Los
Angeles.
How We Figure the Moon
Things like the moons diameter
and distance are figured rather
simply by triangulation; its mass
is determined by its behavior in
orbit and, among other things, by
its tidal effects on the waters of
the earth.
Astronomers say the gravita-
tional effects of the moon are re-
spOnsiole for about two thirds of
the oceans tides, while the sun
accounts for the other one-third.
This, despite the fact that the
moon is hardly more than a speck
of dust alongside the sun.
The factor of distance makes
the moon pre-eminent in creating
tides. because gravitational effects
attenuate rapidly with distance.
The distance factor also creates
another interesting phenomenon:
Solar eclipSeS.
The sun is Just about 400 times
as far from the earth as the moon