South Bend news-times. (South Bend, Ind.) 1913-1938, 1919-06-29
The Heavens in July
BvDr. c. s. Brainen of Columbia University

Shortly after sunset the western
sky VIII show 4. particularly fine
grouping Of planets and stars
Venus, the brightest planet of all.
Saturn, the unique planet with the
rings and Regulus Of Leo viii be 50
close together as 10 form really
single picture. 10 will be well worth
observation. ard We would recon-
mend 10 those who want q little
closer insight into celestial affairs
10 note carefully from night 20 night
the relative positions OF the three.
Venus Is the brightest. saturn is
next, and the star Rekulus. although
IN itself Of first magnitude. is the
least brilliant Saturn Is somewhat
yellower in color thar the other
two. Another point that may nelr
ia recognition Is that planets twin
kle very little even on nights when
the stars are twinkling vigorously,
and on most nights rot ar all.
Mercury, which is the closest
planet 10 the sun, occupies a place
on our map this month. This is q
rare occurrence, for Mercury is so
close TO the sun that il scarcely ever
is above the horizon at a late enough
hour. Venus ana Mercury both
have the same kind of apparent mo
ton in the heavens. They swing
like pendulum hobs about the sun
as a center. never exceeding a Ger
tain number of degrees from it. But
Venus range is much greater than
Mercury's. for its orbit lies outside
that Of the latter. therefore. il APP
pears quite often on our map and is
a familiar sight TO US ALL
Mercury viii be at the eastern
end of one OF these pendulum-like
swings on July Il, and the proper
time for trying TO observe il Will be
within one week preceding and one
following. Venus also is at the
eastern end Of it's swing, OF greatest
eastern elongation. this monitor
the seventh: but this makes little
difference in the observation OF
Venus. 1t will remain in the heav-
ems several months Yet. In the tel
escope both planets show phases
very much like the moons
Perhaps no more fitting month
than July. 1919, could be found for
a discussion or our satellite, at any
rate. it has always appeared 20 Us
that the beauties Of mOonshine arc
more appreciated i'm summer than
in winter. AS the earth passes
around the sun IN its yearly robital
revolution, it carries with it the
moon which in turn may be said 10
pass around the earth in an eIhpSe
similar 10 the eaTth's orbit. Ii would
be a true ellipse Il the earth itself
were still, bat in reality the actual
orbit of the moon about the sun
is very complicated.
The average distance from the
earth is a little less than 100000
miles. but this is a convenient fig.
ure to remember. The moon per-
forms its orbital revolution in p IA
days. though the time between two
similar phases, say two fun moons.
is longer, 291-2 days. This is, Of
course. tho origin Of the month and
week; hour, day and year have Their
origin in the axial rotation and o.
5ital revolution of the earth.
If one notes carefully the posi-
tons of the moon with respect 10
the fixed stars at the same clock
time on a number of successive
nights, il Will be seen that the moon
moves considerable distance
through the heavens in one day; IL
fact, since it has TO pass from a
given star back again to the same
star in about 81 DAYS. it has 10 pass
over 12 degrees in p hours. More
over. il will he noticed that, though
the apparent rising and setting
movement of the moon is from east
10 west, as with all celestial bodies,
its progress through the starry field
is from west TO east For that rea-
son, il reaches the meridian of any
town one hour later, on the average
on each successive night Fne moon
is the principal cause Of the ocean
tides, and this explains why the
high and low tides come about an
hour later each day.
The moon is about 2.l60 miles
in diameter, and its surface area is