The gazette-times. [volume] (Heppner, Or.) 1912-1925, 1914-07-16
~HAT are the dimensions of the
" smallest object which could be

~ sHallest OBJECT which could be
perceived by the human eye
studying the moon through a tele-
scopeY Laymen ask the astronomer this
question frequently, and it is not so
easily answered as might be supposed.
They ask, GLOW near do the most
powerful telescopes bring us to the
moona Would we be able to see human
beings if they wero walking around
theref" The scientific question is,
"What is the size of the smallest object
that We could distinguish on the surface
of the moonl"
Arago states in his popular Astron-
omy" that as the moon is 23S,S50 miles
away, a telescope magnifyng it ten
times ought to bring it with 23,s85
miles, a magnification of 100 times
within .2,3SS miles, and magnifica-
tion Of 1000 times to within 23S miles
of the earth, so far as vision is con-
cerned.
What could we see on the moon at a
distance of 23S milesY Hardly anything
in detail, for all would be beyond the
power Of sight. And besides where is
tho astronomer who can hope to OBJ
tain a magnification Of 1000 times
The conclusion must be that we can
hope to distinguish upon the surface
of the moon only very large objects,
such as mountains or huge craters.
According to Arago's reasoning, if
we could secure magnification of
1900 times it would be as if we were
looking at some object on earth re-
moved to distance Of ll9 miles.
But this reasoning is all wrong when
applied to a star high above the horizon.
near the zenith of the heavens. In
this case our eyesight has to pass
through layers of air equal only to that
between US and an object five miles
away on earth. The problem must there
fore be attacked from another, more
scientific side, before the question can
be properly answered.
On account of the limitations of
vision of the human eye, even when
aided by the most powerful telescope,
the figures given before must be cor
rected. If we get an enlargement of 10
times the amateur can see objects l,S0Q
feet in diameter. If our eye could use
a telescope magnifying 1000 times the
object seen on the moon might be
only 100 feet in diameter and 1000
times only 81 feet in diameter But
this is only theoretical.
Practically the case is quite different,
for the power of the eye is now the
main consideration. The eye may be
trained even for astronomical observa-
ton, so that it sees more than the un-
trained eye. But then we are face to
face with another difficulty, that of
the atmosphere The wider the opening
of the telescope the greater are our
difficulties with the atmosphere. The
image becomes SO trembling and in
distinct when looked at through the
larger telescopes that we see hardly
anything.
theoretically we should have to Sc
cure an enlargement of 5000 times to
see an object "a feet in diameter, and
if we wanted to see something yard
in diameter the enlargement woulu
have to be $4,000 times. Even II we
ever get telescope of this power the
human eye will not be able to see
through it, even though we place the
telescope upon the highest mountain so
as to escape the thickest layers OF the
atmosphere. =, ,.
The greatest astronomers, like Sir
William Herschel have made their most
valuable discoveries by comparatively
low power telescopes. The eye OF man,
unless some new laws of optics are dis
covered, will never be able to see any
small object on the moon, no matter
how powerful our telescopes are made.
We may see mountains and craters-
that is about all.