The fourth planet in distance from the sun, and, next to Venus, the one
that comes nearest to the earth, has also to the latter some points of
resemblance. Not that it is like it in size; for in fact, it is not more
than about one-eighth as large; nor yet in the length of its year, which
is nearly twice as long as one of our years (about 687 of our days).
But it has about its equatorial regions, light and dark portions, which
are generally admitted to be continents and oceans, whose distribution
appears very much like that of the land and water on the earth’s surface.
About the poles also appear during the planet’s winter brilliant white
portions, which disappear during its summer. This is probably occasioned
by the fall of snow in winter, and its melting in the spring and
summer. Again, its time of revolution on its axis, which has been quite
satisfactorily determined, and, indeed, much more accurately than that
of any other planet, is shown to be 24 hours, 37 minutes, 23 seconds
very nearly, making its days and nights very much like our own. Its
seasons also resemble ours somewhat, though longer and subject to greater
extremes of heat and cold. The inclination of the equator of Mars to the
plane of its orbit is about 27°, or 3½° more than that of the earth;
and its year being nearly twice as long and its orbit more eccentric,
make the seasons in its northern hemisphere about as follows: Spring
191⅓ days, summer 181 days, autumn 149⅓, and winter 147 days (of the
planet). When nearest to us, its apparent diameter is about seven times
as great as when farthest away. These distances are in round numbers
35 and 247 millions of miles respectively. It appears brightest to us
of course, when in opposition, that is, when we are between it and the
sun, its distance from the earth at these periods varying from 35 to 62
millions of miles, making it seem four times as bright at the former as
at the latter distance. On account of the inclination of the equator
to the orbit, we can see 27° beyond the north pole at conjunction, and
27° beyond its south pole at opposition; hence astronomers are much
better acquainted with its southern than with its northern regions. It
is believed that Mars has not only land, water and snow, but also clouds
and mists. The land is generally reddish when the planet’s atmosphere is
clear; this is owing to the absorption of the atmosphere, as is the color
of the setting sun with us. The water appears of a greenish tinge. Of
this planet we have to report for this month, that it is decreasing in
interest. Its diameter diminishes from 7.8″ to 6.6″. On the 2d it sets at
1:34 a. m.; on the 16th, at 12:55 a. m.; and on the 31st, at 12:13 a. m.
On the 2d, at 9:01 a. m., it is 7° 9′ north of the moon; on the 5th, at
midnight, 90° east of the sun; on the 30th, at 3:20 p. m., is again in
conjunction with and 5° 50′ north of moon; and on the 31st, at 11:00 a.
m., is 58′ north of _Alpha Leonis_.