Evening star., 1936-06-18
STARS, MEN AND ATOMS
Notebook Of Science Progress in Field,
Laboratory and Study.
BY THOMAS r. HENRY.

chance that the Siberian skies will be
clear.
Dr. and Mrs. Gardner are especially
concerned in getting clearly defined
photos of the suns corona, the halo of
pearly light extending for thousands of
miles out into space around the solar
disk; the great, red, flamelike protuber-
anceS Of hydrogen large enough to en-
gulf the earth which shoot out into space
at enormous speeds from the suns edges;
and the chromoSphere. the crimson at
mosphere several thousand miles deep
which surrounds the sun. These fea-
lures are present at all times, but are
hidden by the intensity of the suns
light Only when this light is obScured
by the shadow of the moon can they be
seen.
The corona appears only at the mo-
ment of totality, when the sun is COM
pletely covered by the moons disk. The
nature of this crown Of pearly light has
been a mystery which scores of eclipse
expeditions have failed to solve satisfac-
torily. 1t now is believed, however, that
the sun is surrounded by a tenuous
atmosphere Of molecules, atoms and
electrified particles, extending hundreds
of thousands of miles out into space,
and that the corona may be this atmos-
phere seen by the light of the hidden
SUM- One of the objects Of the expe-
dition will be to obtain accurately the
spectra of the corona. The spectroscope
divides light into its various wave
lengths, and these enable physicists to
determine the elements present.
During the clipSe the moon will move
between the earth and the sun, and the
resulting shadow of the moon will trace
q 50-mile-wide path Of darkness from
the Mediterranean Sea eastward across
Asia, through Turkey, Russia, Siberia,
Manchukuo, Northern Japan and out
into the Pacific Ocean. The moon will
be 231 400 miles from the earth during
the eclipse and the sun will be "a 500 900
miles away. Although the sun is about
865, 900 miles in diameter as against 2,l60
for the moon, the former is completely
hidden because of its tremendously
greater distance from the earth.
The last total eclipse of the sun visible
in the United States occurred in New
England on August 81, 1882. The next
one in this country will be on July 2O,
1868. Seven-minute one is due next
June IN Lne mlQOie Oh Lie FhClliC StCdi
but no plans have yet been worked out
for observing 1t.
All solar eclipses are eagerly followed
by astronomers, because of the extreme
Importance of the sun to all earthly az
fairs. Especially significant this year will
be DIR. McNallys observations of the
exact time at which totality begins and
ends. and the times when the moon be-
gins to move across the face of the sun
and when the sun completely emerges
from behind the moon. This will serve
as a check on the predicted time of the
eclipse and on the movements of the sun,
moon and planets-the computation Of
which is a special function of the Naval
Observatory.
The corrections, however, will be only
extremely small fractions of seconds.
The elements of the eclipse were pre-
dicted five or six years ago by DIR. James
Robertson, director of the United States
naval almanach Office, who is the official
eclipse predictor for the world.