The Guthrie daily leader. [volume] (Guthrie, Okla.) 1893-1996, 1912-07-09

! heighborhood OF the planet, thu
completing its 16-day circuit
| II must be remembered that,
though the moons are moving around
| Jupiter in almost circular orbits
Us. so that the moons apparent mo-
lion is almost in a straight line,
hack and forth along the ecliptic.
or course the moons appear in
many different combinations. On the
night of July l Satellites and Ii.
are TO the east OF the planet, III and
". to the west On the night of
the 4th, when ~ is at its farthest
west, L., II and III lie strung out
to the eastward in the order given.
On the night of July all four may
he seen east of Jupiter, again lined
up in the order OF their numerals.
Ec.ipses, Transits, Occulations
On certain occasions one of the
moons will be invisible This means
that il is either in transit (moving
westward across the bright face OF
the planet) or else in eclipsed (lost
In the planets shadow or occuted
(nidden behind it's disc) Two moons
iodt Dc Oot vi Sight al the SdiHE time.
1t is even possible for all to be in
visible at once leaving Jupiter, as
viewed from the earth, a moonless
planet. This is not to be wondered
at since the moons, except in the
case OF the fourth, are eclipsed at
each revolution
Astronomers foreteil all these phe-
nomona with great accuracy. The
predictions can be found in the Nau
teal Almanac. in which also the rela
tive positions OF the satellites from
night TO night are diagrammatically
set forth
How Speed Of Light 10 Found
The eclipses OF Jupiter's moons
have been put to practical use In de.
termining longitude. II was by OBJ
serving them, too, that astronomers
were first able to compute the veloc-
ily OF light. For they found their
predictions going wrong in a very
orderly manner, the eclipses falling
behind hand as the earth. in its an
nuai Journey around the sun, receded
from Jupiter, and catching UP as the
earth again approached the giant
lianet. They found that between op.
position (when the earth Is between
the sun and JUPITER and conjunction
twhen the sun IS between the earth
and Jupiter) the total retardation oil
the eclipses was 16 minutes and 80
seconds 1t became evident that this
was the time required for the sun.
light reflected to us from Jupiter's
moons to travel the extra distance
measured by the diameter OF the
EARNS orbit and hof
lngly twice the time required for
lght TO travel from the sun to the
earth The suns distance being |
Known the speed of light could thus
be computed.
Modern astronomers have reversed
this process. They have determined /,
The velocity of light by experimental !
methods more exactly than was pos |
slble by that just described, fixing 1t !
az l66.324 miles q second. Then, |
knowing the time it takes for sun
light to reach the earth, they have Z
been able TO calculate the SUMS dis /
lance with great accuracy and, from
That astronomical unit" the dis.
Iances OF other heavenly bodies.
On the night Of July 23, Jupiter /
viii be near the moon, which ia then
nearing full and from that time on.
as well as for two or three nights
previous, il will not be so easy TO
watch the motions OF the satellites
as earlier in the month
New Consultations on View
The Summer span OF the Milky
way is now well above the horizon
md new lot of consultations IS
fitting into view. One side of the
ireat Square of Pegasus is visible AZ
he hour OF the map and the whole
igure is displayed two hours later.
To the southwark Sagittarius THE
Archer) and Capricornus (The Goat
ire added to zodiaeaI groups. replac.
ng Gemini and Cancer. now just be-
ow the western horizon. yt
The inverted Milk Dipper in Sagit-
arius is well marked .configuration,
,eing composed of FIVE stars bf the
second and third magnitudes The
igure OF the Archer is not plainly de-