Evening star., 1952-05-09
World Declared Covered
By Magnetic Umbrella
But 1t Is Slightly Leoky
At Poles, Scientist Finds
BY Thomas R. Henry
he world has magnetic umbrella.

The world has magnetic umbrella.
This umbrella is slightly leaky some
where in the neighborhoods Of the two
magnetic poles and rain gusts of cosmic
particles get through. That is the rea-
son Tor the aurora borealis in the north
and the even more brilliant aurora aus
trails in the south.
Such was the thesis presented. in a
highly mathematical form, to the Ameri-
can Geophysical Union meeting jointly
with the American Meteorological Soci-
ETY. by DR.. Donald H. Menzel of Harvard
University.
The sun, Dr. Menzel said is constantly
squirting into space streams of particles.
They consist chiefly Of atoms. or MOLE
cules OF hydrogen gas. The streams
come of the. suns surface as If they
were coming from a fire hose They
move at speed of about so feet sec
ond. Actually the streams are extremely
tenuous. with less than 100 particles per
cubic centimeter.
Particles Nearing the Earth.
When one of these streams gets
through the suns magnetic field which
tends to pull it back to the surface Of
until it hits the magnetic field of the
earth. This field has about FIVE times
the radius of the earth. It acts. DR..
Menzel said, as protective umbrella.
The particles in the stream bounce off
it and tend to diffuSe in a thin cloud
around the earth.
But one of the peculiarities of the
earth's magnetic field, he explained, is
that it has leaky places near the poles
through which particles can break if
they are coming in the right direction
at the right time. Moreover, the field
itself tends to compress the fast-moving
gas. It is as though an umbrella
changed rain into hailstones capable Of
going through it.
1t is the concentration Of these highly
charged hydrogen particles that is re-
sponsible for the aurora. There is.
DR.. MenZel said, an enormous heating
effect over a path from to 10 miles
wide and 1000 miles long. This Is the
aurora as it is seen on earth. It ex-
plains, he said. recent claims to have
detected part of the spectrum Of hydro
gen in the auroral light.
Photographs Show Gas Streams.
DF. MeIlzel mas d TemaTkaDle SET OF
pictures taken at the Harvard OBJ
Servatory station at Climax, Colo, show
ing the escape of the gas streams from
the sun, despite the enormous magnetic
field of the star. They were taken with
a special adaptation of the coronoScope,
with which astronomers now can photo
graph the corona of the sun in broad
daylight. The majority of the spurts
of flaming gas are almost Immediately
pulled back into the sun. In fact,
nearly every photograph shows the gas
as falling instead of rising. Yet it
obviously must have gotten off the suns
surface originally and, as DR.. Menzel
puts it. i've very, very seldom see rain
60 up, but we know 1t does"
The occasional spurts that get of the
solar surface altogether seem to be asso-
ciated in some complex fashion with sun
spots There have been many attempts
to correlate weather on earth with sun
spots Efforts also have been made to
find some relationship between weather
and appearances of the aurora In
neither case has relationship been
proved, but from this evidence 1t would
seem that if it obtained for sun spots
it also would obtain for the northern
lights.