Evening star., 1962-12-27
BY WILLIAM HINES
Star Science Writer

PHILADELPHIA, Dec. 27.-
First reports from the Mariner
2 space probe indicate that the
planet Venus has no magnetic
field.
The information Is not con-
elusive, scientists were told yes
terday. But If it is correct, in
dications are strong that Venus
is quite a different place from
its "twin," the earth. A paper
on magnetic-field findings from
Mariner was read at the OPEN
ing session of the American AS
sociation for the Advancement
of Science here.
Mariner, launched in August,
flew past Venus at a distance
of about 81, 800 miles on De-
cember IA. It neared perihelion
closest approach to the sun
to-day, and will reach that
point 1911 am. (EST) tomor-
row, at a distance Of IS, sos, 1856
miles, the Space Agency an
nounced.
More Data Later
Data on the mysterious
bright planet Venus, which
doubles as morning star and
evening star in the heavens, has
been awaited avidly since the
December IA "fly-by." Yester-
days information, while incon-
elusive in itself, will yield a
clearer picture Of the planet
when taken with other data not
as yet published.
Scientists at Palo Alto, Calf,
will hear about certain other
features of Venus vicinity to-
morrow. The most interesting
information. on the planets at
mospheric and surface tempera-
lures, is not expected for at
least two weeks.
p. j. Coleman Of the Uni
versity of California at Los An
geles reported on findings about
Venus magnetic field. He said
data from instruments aboard
Mariner gave no indication of
a field such as exists on earth
and makes compasses work.
This does not necessarily
mean that Venus has no mag
netic field" Mr.. Coleman said
However, he added, "the obser-
vations are consistent D.. with
the possibility that Venus has
no magnetic field"
Mr.. Coleman hazarded no
gueSses as to what conditions
might be like on Venus, the
earth'S nearest planetary
neighbor. Some scientists think
the planet is covered by great
moist clouds, while others be-
lieve the cloud cover is dusty
in nature. Most observations to
date have indicated tempera-
lures about 600 degrees above
zero.
Temperative Evidence Later
These high readings may
come from Venus ionosphere,
the electrically charged part of
the atmosphere. Mr.. Coleman
suggested. He did not rule out
the possibility. however, that
Venus may actually be that hot
on its surface. Radiometer
readings from Mariner, still
. unevaluated, will tell the story
about the temperature.
Mr.. Coleman pointed out that
the magnetometers seem to
bear out a prevailing notion
that Venus is revolving on its
axis quite slowly. This would
have the effect Of making
Venus day" quite long - the
equivalent Of at least 10 earth
days, and possibly as much as
225 earth days, which is the
length Of a Venus year"
If Venus day is 225 earth
days long, the planet keeps one
face continually toward the
sun, Just as the moon does with
respect to the earth.
This slow rotation may &C
count for Venus weak or non-
existent magnetic field, Mr..
Coleman said. Most scientists
believe a magnetic field is set
up by the so-called dynamo
effect" Of a molten metallic
core inside a rapidly rotating
solid body. This Is an explana-
ton of how the earth gets its
magnetism.
If there Is no magnetic field
30 ed ,,a q ITa,a AIlnw. D.fk