64. The Planet MARS is next in order, being the first above the Earth’s
Orbit. His distance from the Sun is computed to be 123 millions of
miles; and by travelling at the rate of 47 thousand miles every hour, as
in the circle ♂, he goes round the Sun in 687 of our days and 17 hours;
which is the length of his year, and contains 667-1/4 of his days; every
day and night together being 40 minutes longer than with us. His
diameter is 4444 miles, and by his diurnal rotation the inhabitants
about his Equator are carried 556 miles every hour. His quantity of
light and heat is equal but to one half of ours; and the Sun appears but
half as big to him as to us.
[Sidenote: His Atmosphere and Phases.]
65. This Planet being but a fifth part so big as the Earth, if any Moon
attends him, she must be very small, and has not yet been discovered by
our best telescopes. He is of a fiery red colour, and by his Appulses to
some of the fixed Stars, seems to be surrounded by a very gross
Atmosphere. He appears sometimes gibbous, but never horned; which both
shews that his Orbit includes the Earth’s within it, and that he shines
not by his own light.
66. To Mars, our Earth and Moon appear like two Moons, a bigger and a
less; changing places with one another, and appearing sometimes horned,
sometimes half or three quarters illuminated, but never full; nor at
most above a quarter of a degree from each other, although they are 240
thousand miles asunder.
[Sidenote: PLATE I.