"It would require nine and a half globes the size of Mars to make one globe the size of the earth; and even then it would not be so heavy, because the average density of Mars is only about three-fourths of that of the earth. Mars is the next planet outside the earth's orbit, so is the fourth from the sun. The orbit in which Mars moves in its journey round the sun is very much more eccentric than the earth's orbit; in fact it is more eccentric than the orbits of any of the larger planets. As a consequence, the planet's distance from the sun varies greatly according to the particular part of the orbit in which it may be moving. Its mean distance from the sun is 141,500,000 miles, its greatest distance over 154,000,000, and at its nearest approach to the sun, or 'perihelion,' as it is called, its distance is only 129,500,000 miles. Mars travels in its orbit at a mean rate of 15 miles a second.
"As its orbit is also eccentrically placed in relation to the earth's orbit, it follows that its nearest distance from us in any particular years may vary greatly. The nearest possible approach it can make in regard to the earth is a little under 35,000,000 miles; when at the opposite point of its orbit its nearest approach is about 62,000,000 miles from the earth. As the years of Mars and the earth differ greatly in length, and the two planets move at different speeds, the very favourable oppositions can only occur about once every forty-five years; though a comparatively near opposition occurs about every fifteen years. Such a close approach we have just witnessed, and it will be fifteen years before Mars is again so near to the earth!
Drawn by M. Wicks.
Plate VII
"The Martian year is equal to 687 of our days, but as the Martian days are slightly longer than ours, this really represents 668 Martian days.
"The entire surface of Mars contains an area of about 56,000,000 square miles, which is about one-fourth of the area of the earth's surface.
"Its gravity is only three-eighths of the earth's gravity, thus everything upon Mars would weigh proportionately lighter than on the earth, and the amount of labour required to do such work as digging or lifting would be lessened. There would, for the same reason, be greater ease of movement in walking, jumping, or running, and large bulky animals like our elephants could move with almost the same ease and freedom as our goats.