Evening star., 1935-02-03
BY CAPT. FREDERICK HELLWEG,

BY CAfI. FhEDEhlCh nELLNEU,
Superintendent U. S. Naval Observatory.
- UPPOSE told you that the
most beautiful actress in the
world was going to play her
~ most important role in the
very near future; and. after
you had become quite excited about
the prospect, I informed you that
she was going to play at some little
out-of-the way theater, entirely in
accessible to 80 per cent of the peo-
pie of the city. How terribly disap-
pointed you would be!
The two most important celestial ac-
tors, or shall I say the most power
full actor and the most beautiful ac-
tress, are going to stage their most
important and most brilliant spectacle
today. The main feature goes on
at 1921 am, and finishes at 1927
noon, Eastern standard time.
Unfortunately, they have selected
one of the most isolated parts OF
the world for their principal per-
formance. In fact. the center OF the
performance will be staged out in
space about 1000 miles due north of
the point on the earth's disk nearest
the shadow.
The partial solar eclipse today will
begin in the Pacific Ocean, well of
shore, off Lower California. With
lightning speed the shadow of the
moon will race across the earth and
the performance will be finished at
a point in the North Atlantic Ocean,
off Greenland, in longitude about 36
degrees west and latitude "a degrees
81 minutes north.
Eclipses Once Dreaded.
Eclipses have always thrilled the
world and thousands of persons have
spent many thousands OF dollars
travelling to the best positions to
witness them. Before astronomy had
enlightened mankind. people were
terrified whenever an eclipse occur
red. Eclipses we're viewed with super
stitions dread and frightful acts of
brutality were committed in order to
ward off the impending catastrophe.
Ignorance, superstition, and abIect
fear made the people huddle together
and await with fear and trembling
the inevitable.
In order to illustrate just what an
eclipse is, stand in front of a window
in your home and double up your
right hand with the thumb extended.
Then, holding your hand at arms
length, close one eye and look at
your thumb and the objects beyond.
II you view some object nearby, only
a relatively small section Of the OBJ
ject will be covered, or will be
"eclipsed" But, if you view some
object far away, such as an apart
ment house or monument, you may
be astonished at the tremendous area
completely blanked out by your
thumb Now, bring your fist closer
to YOUR face and you will immed1ately
see that your thumb blanks out an
increasingly larger area.
That is exactly what occurs during
an eclipse. The moon Is in the posi-
ton of your thumb, the sun Is the
distant object and the earth Is your
eve. The type Of eclipse depends en-
tirely on the relative positions OF
the sun, moon and the earth. If the
moons position at the time of the
eclipse is far enough away, the disk
of the moon will only cover part OF
the face Of the sun. We will then
have what the astronomers call an
"annular" eclipse.
If you imagine an enormous dough-
nut in the sky with the hole black
and the rest of it brilliantly illumi-
mated, you will then see what an an
nular eclipse looks like, although the
proportions will not be correct.
You all know that the moon re-
wolves around the. earth in a path
called its orbit. This orbit is almost
circular, and its plane passes close
to the sun.
OF course, you all know that the
moon has no light of its own. What
we see on earth Is the brilliant light
of the sun reflected from the surface
of the moon, just as the light is
reflected from a small circular pocket
mirror.
The moon is more than 1000 miles
in diameter and no light can get
through, therefore, the side Of the
moon away from the sun is dark. and
the shadow of the moon sweeps
through space like an enormous cone
with the moon as its base.
The earth Is about 5000 miles in
diameter. It does exactly the same
thing. The side away from the sun
is dark, it is night time on that side.
And the shadow of the earth Is an
other enormous cone of darkness
sweeping through space.
The Inevitable happens as the earth
and the moon spin through space.
Sometimes, one Of them gets In the
shadow Of the other.