Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-08-24
PLANETS OF OTHER SUNS
ARE BELIEVED HABITABLE
Discovery by Science That Natural Laws
Ruling Earth Govern Entire Universe
n Is Back of Suggestion.

The presence Of individual stars in
the outer whorlS of the spiral nebulae
is favorable to this theory. Other sci
entists, however, maintain that the
spirals are not clouds Of gas, but are
star clouds themselves.
Common Origin Apparent.
However, it would seem that the
probability of formation Of planets ut
the same time by either of these the
cries would not tax the imagination.
At any rate, as far as our own solar
system Is concerned, 1t Is obvious that
the sun, its planets and their own
satellites must have had common
origin. The farthest planet from our
own sun, which Is only an average sized
star, is only one ten-thousandth part as
far away as the nearest star. All of the
known planets share with the sun its
motion through interstellar space. They
all move as a whole, with orbits around
the sun, and therefore substantiate the
similarities among the planets exist.
They all revolve about the sun in the
same directions the orbits are nearly
circular Except for some Of the aster-
oids); their distances from the sun
form regular progression expressed by
Bodies law; the more massive planets
are lower in density and revolve more
slowly than the smaller ones, the sun
rotates In the same direction In which
the planets revolve, and the planets
satellites revolve about the planets in
the same direction that the planets
themselves rotate Except in the case Of
the two outer satellites of Jupiter and
Saturn.
Chance Relation Doubted.
Thus we can see q number Of rela-
tions that may not reasonably be viewed
as o pure matter Of chance. Science
believes they have evolved by the same
orderly process. And II this happened
in our own solar system 1t Is probable
that 1t has also happened in other star
systems.
Early attempts to explain this forma-
ton Of the solar system originated with
Kant and Swedenborg and Laplace in
the eighteenth century. The theory is
known as the nebula hypothesis. It
is somewhat similar to the nebula theory
OF the formation Of the stars. When
one great mass Of gas cooled into o
star its rotation increased and the CEN
trifugal force threw out rings Of matter.
This is supposed to have taken place q
sun surrounded by rings Of matter which
slowly concentrated In one spot In their
orbits into planet.
Theory Raises Questions.
Although this theory accounts for
solar system, 1t has faults that are not
explained. First of all, the rings would
not condense but would tend to become
more evenly spaced. 1t can be proved.
The second fault lies in the angular
momentum of the whole system, which
Is SO great In the outer rings that the
matter could not have concentrated.
According to this theory We might ex-
pect to find almost every star sur
total number Of planets in the universe
might run into the hundreds of billions.
However, the older theory has given
way to o newer theory proposed by
Chamberlin and Moulton, which ex-
plains the formation of our solar sys-
tenn by Q huge catastrophe, near
collision between two stars Of which the
sun was one. This Is the theory Of
dynamic encounter or planetesimal
possess motions that at some remote |
epoch brought them swinging about one |
another in hyperholic orbits.
They did not come quite close enough
to collide, but their gravitational forces
produced great tides on their surfaces
ana drew OUT large masses OF matter
from each star as they approached.
Then they drew apart again and the
elected masses had q lateral motion
impaired to them and portions Of these
gases started revolving around the sun
and another portion revolved around
the other star. From these revolving
masses the planets were formed.
Accounts for Rotation.
This theory accounts for the rotation
OF the sun itself and the rotation of the
planets around the sun. The time for
this process to take place, including the
cooling down Of the planets, has been
calculated by Jeffries as roughly 7,OO0,-
600, 900 years. According 70 this theory,
which is becoming more generally ac-
cepted, the formation Of planets would
be dependent on chance. They would be
formed around stars only when two of
the latter closely approached each
other. But even at that, among the
billions OF stars the numerical proba-
bility of this happening might run into
hundreds Of thousands through the
cons Of past time.
Although such occurrences might be
considered rare" fundamentally, 1t
appears quite unjustiflable to assert that
the earth is the only habftable planet
or that the planets of our solar system
are the Of1lV OYnx In eYistauee