Evening star., 1947-11-10
stors, Men and Atoms
Busic Einstein Prediction
On Relatively Confirmed
Yale and Naval Observatories Find
Shift in Perihelion of Mercury
Bp Thomas K. Henry

One of the three basic predictions Of the
theory of relativity-the displacement of the
perihelion of the orbit Of Mercury-appears to
have been confirmed in q cooperative study
carried out by DR.. Gerald NJ Clemence of the
United States Naval Observatory and astron-
omers of the Yale Observatory.
When Albert Einstein first propounded the
relativity hypothesis about 30 years ago he pre-
dicted three unobserved phenomena. First was
the bending of the light from distant star as
it passed near the sun. This has essentially
been confirmed by dozen total eclipse expedi-
tions. Second was a shift in the spectrum Of
light from an object in motion. This also has
been observed.
Far more difficult to confirm was the third
prediction-that the point in the orbit of Mer-
curry at which the planet was nearest the sun
would differ from year to year by minute
amount which could not be accounted for by
the gravltational attractions in the solar system.
Difference Extremely Small.
The difference predicted was extremely small
and almost outside the possibility of observa-
ton, especially since there were many COM
plicating factors. In this project DR.. Clemence
has made use of all observations of the posi-
tion of Mercury in its annual orbit taken any,
where in the world between 1765 and 1887.
Previous to the late 18th century any astro-
nomical observations had little reliability. Out
Of this extremely laborious study the orbit of
the smallest of the suns ajor planets for more
than century has been determined.
During this time the point in its path where
Mercury Is nearest the sun has advanced about
five miles-in very close agreement with the
Einstein prediction. This point, or perihelion,
will continue to move forward by an unob-
servable amount each year, according to astron-
omerS here
The same study has shown an hitherto I'M
practicable relativity variation in the orbit
Of the earth itself. The perihelion of this
planet moves forward in the same way and for
the same reason as does that of Mercury but
to very much smaller degree. The total
shift is only about so miles in a thousand
centuries-an amount which would have
escaped detection had not DR.. Clemence looked
for 1t with the example of Mercury in mind.
Perihelion Shift Greater.
The shift in position of the periheion of
Mercury, because of its closeness to the sun,
is much greater. If as great a relatively effect
applied to the earth 1t would result in con-
siderable climatic changes.
Yale Observatory and the Naval Observa-
tory are cooperating in laborious study to
fix the precise movements of the suns prin-
ciple planets, now possible for the first time
because of the extremely rapid automatic
electronic calculating machines developed
during the war. The same degree of accuracy
has not hitherto been possible and the last
comprehensive analysis in planetary move
ments was carried out entirely with pencil and
paper by Prof. Simon Newcomb at the Naval
Observatory about so years ago.
The work, 1t was announced, already has re-
suited In an entirely new mathematical theory
of the motions of the great planets Jupiter
and Saturn. With the system used up to now
predictions of the positions Of these planets
would be more and more In error the greater
the time lapse since they we're made. Not only
is it now possible to consider a far greater
number of observations but these observations
themselves, made photographically instead Of
usually, are far more accurate.