Evening star., 1953-05-13
Milky Way Is Larger
Than Earlier Estimates
200 QuodriIIion Miles
Added to Locul Cluster
By Thomos R. Henry

By Thomos R. Henry
The radius Of the Milky Way galaxy,
the great island universe" OF more
than 100 billion stars including all the
visible heavens, Is about 200 quadrillion
miles greater than astronomers have
believed.
It is encircled, far in space, by q
crown Of clusters Of stars, which can
be considered the farthest frontier Of
the system in which the planets Of our
solar system are like indistinguishable
grains of dust.
This finding was reported to the Ma
tional Academy of Sciences here by Dr.
Harlow Shapley, Harvard professor Of
astronomy, and Ann B. Hearn of the
Harvard staff. It is based on measure
ments Of the distance of star clusters
in the crown by observations of a
peculiar type of variable stars, the fire.
quency of whose periodic increases and
declines in radiation constitutes o
rough criterion Of their distance.
Observations Difficult.
The Harvard astronomers observed
"a such variables over q vast extent of
the heavens but their conclusions are
based on only IL Of these because Of
the difficulties in getting reliable OBJ
servations.e 1t is difficult, for example.
to estimate the amount of "star dust"
which absorbS radiation, between a dis
tant star and an observer on earth.
The reliable observations, DR.. Shap-
ley says, indicate that the star clusters
of the Milky Ways crown are at a
CT ~ of Iii
approximately 500 quadrillion miles.
Their light requires about $4,000 years
to reach the earth. Previous estimates
have placed them at a distance of about
$4,000 light years.
These clusters. DR.. Shapley says in
his report of the investigation carried
out with the aid Of the Office Of Naval
Research. are very thinly distributed in
the great crown around the universe.
They probably add only an inappreci-
able. unmeasurable amount to the total
weight Of the star system.
Great Outer Void.
Between them and the great body Of
the Milky Way galaxy is a circle Of
space almost destitute of stars. Beyond
them, so far as known, there is nothing
until the next nearest island galaxy.
the great nebula in Andromeda which
is about equivalent to the Milky Way
system. 1t lies across void raversed
by light in about 100000 years. Only
exceptions are the two Clouds of Magel-
Ian, visible south of the Equator. which
are vast aggregations Of stars consid-.
cred as satellites of the Milky Way sys-
tenn much as the moon is a satellite
of the earth. Still they are independent
stellar aggregations.
The dimensions of the Milky Way,
when it can be determined without
much uncertainty, will constitute one
of the most important measuring units
in astronomy. It will constitute the
first step toward determining accu-
rately the size and distance of the near
est Of the millions Of other galaxieS
which now can be discerned in the far
depths of space. The bounding Of
creation itself, at least to the greatest
possible observable limits. is the major
job now assigned to the worlds largest
telescope, the 2O0-inch Mount Palomar
telescope of the Carnegie Institution Of
tute of Technology.
w W dbOuC AO yCd1o dSO, J1lC V1l1hy
Way comprised the universe, as man
knew it-a great conglomeration Of
stars buried in nothingneSS which ex-
tended infinitely in all directions. Esti-
mates Of the size of this galaxy were
much smaller then than now. Estimates
of the number of stars and the radius
they fill have gone up almost every
year.
Others Discovered.
Then came the discovery of the An
dromeda nebula as an object compa-
rable in size and general constitution
with the Milky Way galaxy itself. Then.
in rapid succession, came the discovery
of clusters of nebulae-the Milky Way
itself and the Andromeda spiral were
just two out of eight or ten members Of
one such cluster, scattered through the
whole depths of space.
For some years astronomers held
that, after all, the Milky Way star
cloud was giant among galaxies. Thus
far this cannot be successfully refuted.
as nothing bigger has been found. Still
all observations indicate that the An
dromeda galaxy is just about as large.
Some Of the star systems in the local
cluster, however, are considerably
smaller. There Is no good reason to be-
lieve that some of those discerned in
the far depths Of space may not be
much larger.
The Milky Way galaxy remains. how
ever, the only one on which anything
like precise measurements can be made.
If the Andromeda nebula. for example,
is surrounded by crown of star clus-
ters, it probably will be impossible ever
to discern them over the vast gulf Of
space.