The watchman and southron. [volume] (Sumter, S.C.) 1881-1930, 1909-07-07
THE EARIH'S MOTIONS
How We Are Whining Around
and Through Space.
The INFLUENCE OF THE SUN.

Wtenout It's Attrc ction That Draws The
World Toward It In an EIIipticai
Course Our Globe Would Wander on
Forever In Straight Line.
There are those who think much of
moving from one point to another Of
the earth-travel they call it-and vet
pay little heed to the wonderful Jour.
ney Of the earth itself. Many. again.
90 to seek climate while the hurry.
Ing earth Is bringing to them one eli.
mate after another In endless success.
sion. Those who have not hitherto
taken much notice Of the earth's prog
ress-who have not. so to speak. looked
out Of their carriage window as they
are whirled along-might find a new
interest In doing so. Look, for exam.
pie. at the apparent size Of the sun.
Casual observation shows that It an.
pears larger In the winter heavens.
And exact measurements tell Us that
1t Ii largest on Jan. / and smallest on
July 2. The size Of the sun thus marks
the earth's nearest approach and
greatest distance from the sun. Accu.
rate astronomical measurement Of the
suns diameter might even determine
the DAY OF the year. for the daily vari-
alton In the apparent size Of the sun Is
soms nine-iftieths Of a second Of an.
gular measurement. And astronomers
profess to measure the second decimal
Of seconds.
These are three ways IN which we
are tOurneytng With the earth. There
u. 6rst the daily revolution. which car.
ries us through q complete circle In
twenty-four hours at a rate varying
from rather more than a thousand
miles an hOur at the equator to moth.
Ing at the poles. where no one, by the
way. has ever been. Then we are trav.
cling around the sun once q year at
the rate Of eighteen miles second.
Thirdly. We are tourneying through
stellar space. for one Of the most re-
markable facts which modern astron.
omy has brought to light is that our
solar system. the sun with all its plan.
cts, iS on q Journey toward the con.
stellation Lyra at the rate Of ten miles
q second.
As we sit In train and are whirled
along 1t sometimes appears as IL the
scenery were flying past us rather
than we past It So the daily revolu-
tiOn Of the earth-a thousand miles an
hour at the eQuator-makes the sun
rise and set. and our yearly journey
makes the sun apparently travel
through the consultations Of the 20.
1iac. II we move round any stationary
object on the earth we see II with a
constantly changing background-now
windmill DOW a cottage, now q
wood. DOW q church. etc. So as we
travel round the sun we see It with an
ever changing background Of stars
now those v. Aries. now Of Taurus.
now Of Gemini. and 80 on. The posi-.
ton OF the sun among the stars marks
the stages OF the earth's annual jour.
ney. And as the earth arrives at DIFF.
ferent points Of It's orbit the times of
the r1singS OF certain stars vary. These
Indications OF the earth's progress
have been taken as marks Of the sea.
sons. Thus when Sirius rose with the
sun It was known that the dog days
bad begun. Early astronomers watch.
ed carefully for the rising of the dog
star. The Egyptian astronomers look
ed for the heiical rising OF Sothis to
proclaim the new year.
It ts the earth'B yearly Journey round
the sun which enables Us to determine
the distances Of the stars. The method
Is precisely that adopted BY surveyors
for determining the position Of objects
ON earth. The direction Of the object
whose distance Is to be found is OBJ
served from two points a known dis
tance apart The rest Is mere calcula.
tion. In the case OF the stars the direc.
tfons are observed from two extreme
points In the earth's orbit instead of
from the two ends of q base line. The
process Is called triangulation when
applied to earth measurements, and
everybody understands what it means
When applied to the stars It is called
parallax and remains q mystery to
most people Such Is the obscuring
power Of q word.
The little more" and the little less"
OF Browning are forcibly illustrated in
the direction Of the earth's journey
round the sun. An elliptic course diff
fering very little from a circle, COM
bined with tilt Of the axis, gives us
the seasons. But II this difference and
tilt did not exist there would be no
seasons and one climate would rule
the year. If, again. the course were
more elliptic, then for the hemisphere
whose winter occurred at the earth's
greatest distance from the sun there
might be q glacial period.
THE straight line." says Miss Helen
Keller, "symbolizes duty. 1t Is q dull
thought drawn out endlessly." And
this seems to be a reflection on what
we bad thought was th0 eArth'a path