, 1877-12-07
Mars.

When Galileo turned towards Mara .bo
telescope with which he had discovered the
moons of Jupiter,the crescent form of We.
nus and many other wonders in the heavens
he was altogether disappointed. His tele.
scope was indeed too small to show anv
features or interest in Mars, though the
planet OF war is much nearer to us than
Jupiter. Mars is but small world Tho
diameter OF the planet is about 4,400
miles, that OF our earth being nearly
S,OOO. Jupiter, though much farther
away, has his immense diameter of more
than $4,000 miles, to make up for the ef.
feet OF distance. With his noble system
OF moons ne appears remarkable OBJ
Ject even with small telescope, but
Mars shows fewer features of interest
even with telescopes of considerable size.
twas not, then, till very powerful tel
escopes had been constructed that astron-
omers learned what we now know about
Mars.
1t is found that his surface is divided
into land and water, like the surface of
our own earth. But his sess and oceans
are not nearly so large compared with his
continents and lands. You know that
on our own earth the water covers so
much larger surface than the land that
the great continents are in reality islands.
Europe, Asia and Africa together form one
great island; North and South America
another, not quite SO large; then come
Australia, Greenland, Madagascar, and so
forth; all the lands being islands, larger
m al IN
the Caspian Sea and the Sea of Aral, there
are no large seas entirely land. bound. In
the case of Mars u very different state of
things prevails, as you will see from the
three accompanying pictures (hitherto
unpubished), drawn by the famous Eng
lish observer, Dawes (called the Eagle
eyed) The third and best was drawn
with telescope constructed by your ia
nous optician, Alvan Clark, of Cam
bridge, Massachusetts. The dark parts
are the seas, the light parts being land, or
in some cases cloud or snow. But in
these pictures most of the lighter portions
represent land for they have been seen
often SO shaped, whereas clouds, of
course, would change in shape.
The planet Mars, like our earth, turns
on its axis, so that it has day and night
as we have. The length of its day is not
very different from that Of our own day.
Our earth turns once on its axis in -,
but before reading on, try to complete
this sentence for yourself. Every one
knows that the earth's turning ON its
axis produces day and night, and nine
persons out of ten, if asked how long the
earth takes in turning on its axis, will an
swer, "a hours; and If asked how many
times she turns on her axis in year, will
say 1868 times, or if disposed to be very
exact, "about 1861 times" But neither
answer is correct. The earth turns on
her axis about 366l4 times in each year,
and each turning occupies % hours, So
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
necessary to mention this, in order that
when tell you how long the day of Mars
is, you may be able to correctly compare
it with our own day. Mars, then, turns
on his axis in "a hours 81 minutes 20 sec
onds and tenth-parts of second. So
that Mars requires Al minutes IS seconds
and six-tenths 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, how
ever, only about 80 minutes longer than
that of our common day.
Mars has long year, taking no less
than 6S7 of our days to complete his cir
cult 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 northern regions more fully into sun
light, at which time summer prevails
there and winter in his southern regions;
when at the opposite part Of his year his
southern regions are turned more fully
sunward and have their summer, while
winter prevails over his northern regions.
Around his poles, as around the earth's,
there are great masses OF ice, insomuch
that it is very doubtful whether any in
habitants of Mars have been able to pen
citrate to the poles, any more than Kane
or Hayes, or Mares or Parry, despite their
courage and endurance, have been able to
reach our northern 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 reduced in extent, as il natural,
while in winter they reach to low lati-
tudes, showing that in parts of the planet
corresponding to the United States, or
mid Europe, AS to latitude, bitter cold
must prevail for several weeks in success
sion.-Prof R A. Proctor, in 81. NschoIds.