Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1920-11-21
ORBIT OF MOON CAUSES
ITS CHANGES nF SHAPE
Earth Rcvolycs Around Sun in
Plane of Ecliptic, Which,
Brings EcIipScS.

why is the moon when IL is new
sometimes 50 Tar north and again 90
FAR south? | think IL is because our
earth In it's revolution around the
sun carries the moon with IL, making
its orbit extremely irregular. An
other question: When IL Is new moon
here II Is new moon in China and
the same with full moon. e.. il is
fun moon and the new moon on every
Please answcr.-H r Der: Poston,
Athens. Ohio
fou have. in substance. suggested
the correct explanation OF your first
question. The earth revolrcS around
the sun in certain plane. which We
call the plane of the ecliptic. for the
reason that ali oclipses occur near
that piano. You may think Of the
plane of the ecliptic as sort of in
visible circular floor on which the
earth rolls around tho sun.
Then imagine the moon rolling
around the earth on another similar
bu; much smaller floor t,he plane OF
The moons orbiO. which Is slightly
earth's orbit. The amount of this in
clination is. on the average. only >
degrees minutes. I, varies q little.
alternately increasing and decreasing
one-hfth Of degree.
Now, the earth and the moon, al
though they are not rigidly connect
ed. travel together around the sur,
the moon at the same time revoivins
planes in which they move are SO
nearly 'on the same level" IL fol-
lows that when the moon passes be-
tween the earth and tho sun tas at
new moon). IL must he in that part
Of the sky where tho sun is situated.
!. g. il tho sun is north, SO is the
moon.
Nearer Northern Pole.
Again. owing to the fact that the
plane or the car;h's orbit IS tipped
Is l-2 degrees from the plane of the
ca2ator. i. G. the plane In which tho
earth rotatcs on It's axis. will. tina;
way il space. II follows that during
half OF each year the sun is nearer
the northern pole OF the axis and dur
ing the other half nearer the south
pear north OF the plane of the equa-
tor in summer and south of it in
winter. But since, as we have seen
above, the new moon must always be
never he more than about five degrees
away from il. II is evident that tho
position OF the new moon must SHIFT
north or south when the sun shifts
north or south.
III midwinter the now moons a?-
pear low in the South because the
sun is low in the South. In midsum-
mcr the new moons are high toward
toward the North. Bat when the sun
is less than five degrees north. ii Is
possible for the new moon 10 ap-
pear little south OF the equator.
this possibility being due 10 the In
clination nj the moons orhital plano
10 Tire ecliptic. But, in general. II
the sun is north OF the equator the
new moon is north, and il the sun
s south the new moon is south. Thu
exact situation of the moon varies be-
cause OF a periodical! shifting around
of the plane CT its orbit. making the
line OF It's intersection with the
carth's orbital plane describe a COM
plete revolution once in nineteen
years. But this does not affect the
general situation as described above.
Second Question Answered.
Now for the second question. I:
is only true in special sense that
the new moon. or tho full moon. is
visible simultaneously from opposite
sides or the earth. The cNac: phase
of new moon. for instance. occurs
only at certain absolute times. when
the moon Is in conjunction with the
sun, and only the inh;/itnnts OF that
part of the earth which happens 4;
the time TO face toward the position
OF the moon and sun are III a posi-
ton TO see such 81 phase which they
cannot really do because the moon
| is then In the eye of the sun. But.
popularity. we call The moon "ncw'