Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1901-06-22
The June Skies.

ne JuHe okiCS.
The most conspicuous object in the
sky during the short June nights VIII
hc .Jupiter. low in the southeast anu
soutb with Saturn, much less brlghi'
n short distance to the cast. Inc TWO
planets are now moving slowly 10 the
west among the stars in their retto
grade motion. and. in consequence OF
the more rapid motion OF Jupiter are
slowly separating. by september 'he
retrograde motion will have ceased.
and the two planets will be moving
eastward with gradually increasing
speed Jupiter. making the eastward
circuit of the heavens in eleven years.
will overtakc Saturn. moving much
more deliberately eastward. in pc
Rod of thirty years; and by the END OF
November will pass By. nearly
moons diameter to the south.
That Jupiter is much brighter than
Saturn, several times as bright. IN
deed. IL evident. Eut to estimate with
any approach to the truth the number
of times as bright. without instru-
ments of mea surement 10 assist the
vision is something quite beyond hu-
man psychology. In fact. even the
measures are not rs accurate rs might
be desired. when the photometer Is in
troduced to suppress a measured per-
Centage of Jupiter's light, SO as to
have the image seen by transmitted
portion. varied at will. TO he adjusted
equal to the undminished image Of
Saturn.
The brightness of either planet varies
considerably from time To time. The
planet is sometimes a little farther
from the sun than the average. and so
is less strongly lighted by the central
luminary. on whom he is entirely de-
pendent for the light ne sends out He
is somewhat nearer 10 the earth when
both are on the same side of the sun.
ana 50 he looks q little bigger dn the
telescope and seems little brighter
than when they are on opposite sides
of the sun. Ana in the case of Saturn
the splendid ring may be cdgewise
toward the earth. when. on account of
it's excessive thinness. the light from il
is substantially nil: or the ring may he
turned UP toward us at such an angle
that its apparent short diameter is
half its long diameter. in which case
the ring gives fully as much light rs
the bah OF the planet.
Assuming that the reflective power
of the surface of Saturn is equal to
that Of the surface of Jupiter the
theoretical ratio of their brightness is
really calculated. Taking the planets
IS now situated. the distance If Saturn
is almost double that of Jupiter. so
that. in accordance with the law of
inverse squares. unit Of surface on
Saturn would receive from the sun
scarcely more than Il fourth as much
as unit oc surface Of Jupiter: the
distance of Saturn from the earth is
triile over double that OF Jupiter. 50
that If Saturn's actual radiation were
equal to Jupiters he would seem from
the earth to be scarcely q fourth as
bright. OF the suns radated light.
then. Saturn renders to the earth one
sixteenth as good an account per unit
OF surface as Jupiter. As the diameter
of Saturn is 10000 miles and that Of
Jupiter S6.50o. the ratio of their sur
races is about as two to three which
would give for the light from the ball
OF Saturn about one-twenty- fourth. or
four per cent. of the light of jupiter.
The light from Saturn's ring, which IS
now only beginning to recede from its
widest omen position. may be taken
equal TO that from the ball. SO that the
total light from Saturn should be if the
rejecting powe" Of the surfaces of the
two planets is equal. eight per cent. of
the light from Jupiter That the sur
fac"-re ilec ting power is the same in
the two cases seems not to he quite
true: photomct:ic measures of the
briiilancy of two planets carefully
taken. and compared with their
theoretical brlliancy. indicate that the
surface of Jupiter reflects about sixty
per cent. of the light received. ana the
surface OF Saturn about seventy per
cent. Perhaps it would be safe. Mt the
present tllnc. to take the brightness of
jupiter to be ten times the brightness
of Saturn
After their opposition to the sun in
July noti VIII decline little in bright
ness. Jupiter q little more than Saturn
ASIDE from the ring of Saturn. which
IS absolutely unique. the two planets
"le hluch alike. Tney are much
larger than any of the other planets of
the solar system. They both have a
very low density, Jupiter a little more.
saturn q little less. than water. Both
are brighter at the centre than at the
edge, and both have belts as their
chief surface markings Both rotate
IN about ten hours. Their spectra arc
very similar giving strong atmos-
pheric indications. On Jupiter at
ieast the movements of the numerous
spots are Incompatible with solid
surface such as the earths. while pre-
sumabiy Saturn'5 surface is similarly