Warren sheaf. [volume] (Warren, Marshall County, Minn.) 1880-current, 1922-05-03
ASTRONOM
OBSERVATIONS
Keplers Law ON Planetary Motion
By Levi G. Johnson

II
What is known as Kepler's law is
the physical law Of planetary motion
as explained by John Kepler, it's dis
cOverer. "
The discovery of the relative move
ments OF the planets may be credited
to NicOlaus< COpernicus, from Polish
Prussia, who in the beginning Of the
10Th century made up distinct sys-
tenn Of the motions of the heavenly
bodies, which has since been known
as the 'Kopernican system" In ac-
cOrdance with this system the Sun is
the central figure around which the
planets move in certain paths or or
bits, the Fixed Stars remaining sta
tionary And theirs as we'll as the
Suns and Moons apparent daily mo-
ton, is caused by the Earth's daily
turning on it's axis from west to east.
This system almost. astonished it's dis
coverer, by the simplicity with which
the celestial phenomenon could be ex-
planned. Tycho Brahe,, a. Dane, (al-.
though not himself a believer in the
doctrine of Copernicus), was the first
great systematic observer and record
er OF the motions Of the planets. John
Kepler, his student, building upon
these records, by pure brain work sue
ceeded in discovering the true law
governing these motions, viz: That
the speed Of planet in it's orbit is
proportional to the inverse square
root Of it's distance from the Sun.
Example: If the mean distance from
the Sun to the Earth is 92,S97, 416
miles and to Jupiter is 4S3,327 900
miles. Required to find the orbital
speed and time for it's revolution. BY
performing the division we find it's
distance to be 52O2S times the Earth's
distance from the Sun, and by ex-
tracing tho square root we get 22S
which inverted gives us 1OO-22Sth.
Jupiter's speed is therefore 1OO-22Sths
OF 1873 miles per second (the orbital
speed of the Earth) equals S.11 miles
per. second, since the ratio of the
periphery of two given circles coin
cides with the ratio of their radius
The time for Jupiter's revolution is
therefore 5.202S (distance) times 22S|
(ratio of speedy equals ~11.S6. or|
nearly II years.
TO return to our subject, Mr.. KEEP
Ter, on making more accurate tests,
found that the concordance was not
exact, but he was tireless and en-
tered a new field Of exploration which
resulted in another discovery, viz:
That the. orbits Of planets are not
circles but ellipses, and when he put
his imaginary planet into an elipse
of the right eccentricity, it kept even
pace with it's prototype in the sky
and the greatest problem that had
puzzled the philosophers of all ages
was solved It has, however, been
discovered later that the orbits of the
planets are by no means smooth, per-
feet ellipses, but have their irregu-
larities caused by their changing mu-
tual attractions. In connection here
with I wish to mention a very inter-
esting incident which proves to what
degree of mathematical refinement att
which astronomers have arrived. In
the fall of 1916 two astronomers,
Adams Of England and Leverrier of
France, each working without know
ing that the other was engaged in the
same problem, undertook a diagnosis
of the perturbations of the planet
Uranus. Each one reached the con-
clusion that planet must exist at a
distance of nearly one billion miles
further out in space than Uranus, and
that it must be IS times as big as
the Earth and it's year 1855 times as
long. Leverrier informed a friend,
Astronomer Gale Of Berlin, who the
same night and on the exact spot dis
covered the thereto unknown planet
Neptune.
Ac4-