Knoxville journal. [volume] (Knoxville, Iowa) 1874-1986, 1875-05-13

The planet Jupiter, the largest in the
solar system, Is now very prominent
object in the evening sky. He comes to
the meridian near eleven o'clock, having
been in opposition to the sun about two
weeks since.
1t is not necessary to give directions
for finding him, other than that he
is the brightest star visible east from
the southern line; but note OF his posi-
ton with reference To a few stars may
serve as help to recognize them when
the planet has left their neighborhood.
A little to the right of Jupiter, and
southing about nine O'Clock in the even
ing, is very pretty figure--a trapezium
of stars, the upper side of which may
be roughly described as seeming to be
about yard across. This figure is the
constellation COrvus, the Grow. A line
from the two upper stars TO Jupiter will
pass through a bright star, usually classed
as of the first magnitude. 1t Is the prin-
cipal star in Vigo, the Virgin, or the
Cleaner, and is represented on the globes
as in handful of corn carried by the
female. Hence the star has been called
Spica and Azimech. 1t is also called
Arista; not from the Greek word mean
ing "the best" as some may suppose,
but from word signifying the spike of
an ear of corn, or the ear ITSELF.
The constellation Corvus, with its four
principal stars, and two other outlying
ones at opposite corners OF the four-sided
figure, is very easily recognized when
once the observer has identified it in the
sky.
The planet Jupiter has been written
about SO much recently that we scarcely
need essay another description. We
may, however, note briefly the results of
the latest quantitative research, differing
considerably in several respects from the
generally accepted statements of the
| textbooks.
The mean distance of Jupiter from the
sun is All, 500, 900 miles, or a little more
| than 90 times the mean distance of the
earth from the sun. He travels through
space (around the SUM at the rate of a
little more than eight miles per second
His equatorial diameter is $3.50 miles
or 1913 times that of the earth. His vol
ume is 1875 times that of the earth.
His weight (mass) compares with that OF
/ the earth as 305.27 to 1; 10 that of the
/ earth plus the moon as 301 SO to /; and
to that Of the sun as TO 1048 nearly.
Jupiter is attended by four satellites,
the respective diameters of which are
1850 miles, ALTO miles, 3448 miles and
1850 miles. All but the second are
larger than our moon. The third shines
as star of the sixth magnitude, and
could be seen with the naked eye If il
were not partially obscured by the
superior brightness of the planet.
A great deal has been written within
the past few years about the great
changes observable in the atmosphere oil
Jupiter, and the fact that he reflects to vi
SO much light that his temperature must
be only little below the point necessary
to self.luminosity. 1t is believed that
the planet is too hot to permit on his
surface any of the forms of life with
which we are acquainted; and this belief
has been written up in such way OF
ways as to lead many people to think
that the idea Is original with some
astronomers of the present genera.
ton 1t is refreshing to turn to
| the works of the eminent naturalist,
Button, who fourished more than d
century ago, and there find the
whole speculation spread out in abso.
Lutte terms. Button calculated that the
planet had occupied 9,400 years in cool
ing to the solid condition; that he would
occupy 10000 years more in cooling
down to the point where his surface
could be touched; of which period at
least 1000 years are get unerpsred; that
240, 400 years more would be required to
cool the planet down to1he temperature
of the earth; and that still another .483, !
600 years must elapse before the planet
would be chilled down to the present
condition of the. moon.
Button calculated further that three
of the satellites of Jupiter are already
died-out worlds; that one of them, the
largest, is far advanced in the frigid
phase; and..that Saturn will require 81, 00t
! years longer to cool down to the present
| condition of the earth.
| This is pretty good philosophy for q