The central Presbyterian. [volume] (Richmond, Va.) 1856-1908, 1877-11-14
MARS.

When Galileo turned towards Mars the tel
escope with which he discovered the moons
of Jupiter, the crescent form of Venus, and
many other wonders in the heavens, he was
altogether disappointed. His telescope was
indeed too small to show any features of in
terest in Mars, though the planet of war is
much nearer to us than Jupiter. Mars is
but small world. The diameter of the
planet is about 4 400 miles, that of our earth
being 5000. Jupiter, though much farther
away, has his immense diameter of more than
would make up for the effect of distance
With his noble system of moons he appears a
remarkable object even with small telescope,
but Mars shows fewer features of interest
even with telescopes of considerable size.
1t was not, then, till very powerful tele-
scopes had been constructed that astrono-
mers learned what We now know about Mars.
The planet Mars, like our earth turns on
its axis, so that it has day and night as We
have. The length of the day is not very diff
ferent from that Of our own day. Our earth
turns once on its axis in -- but be-
fore reading on, try to complete this SEN
tence for yourself. Every one knows that
the earth'S turning on it's axis produces day
and night, and nine persons out of ten, if
asked how long the earth takes in turning
round her axis, will answer "a hours; and if
asked how many times she turns on her axis
in a year, will say 365 times, or, if disposed
to be very exact, "about 965 IA times. -
But neither answer is correct. The earth
turns on her axis about 366 IA times ip
each year, and each turning occupies %
hours, Sc minutes and seconds and one
tenth of second. We, taking the ordinary
day as the time of turning or rotation, lose
count of one rotation each year. 1t is neces-
sary to mention this, in order that when l
tell you how long the day of Mars is, you
may be able correctly to compare it with our
own day. Mars, then, turns on bis axis in
"a hours, 81 minutes, % seconds, and 7
tenth-parts of second. So that Mars re-
quires Al minutes, 18 seconds and 6 tentbs
of second longer to turn his small body
once round than our earth requires to turn
round her much larger body. The common
day of Mars is, however, only about 80 min
utes longer than our common day.
Mars has longer year, taking no less than
687 of our days to complete his circuit round
the sun, so that his year lasts only about one
month and half less than two of ours.
Like the earth, Mars has seasons, for his
polar axis, like that of the earth, is. aslant,
and at one part of his year brings his north
ern regions more fully into sunlight, at which
time summer prevails there and winter in
his southern regions; when at the opposite
part of his year his southern regions are turn.
ed more fully sunward and have their sum-
mer, while winter prevails over his northern
regions.
Around his poles, as around the earths
there are great masses of ice, insomuch that
it is very doubtful whether any inhabitants
of Mars have been able to penetrate to his
poles, any more than Kane or Hayes or
Mares or Perry, despite their courage and
have been able to reach our north
ern pole, or Cook or Wilkes or James Ross
our antarctic pole.
In the summer of either hemisphere of
Mars, the north polar SHOWS become greatly