Here, said I to myself, is the planet of greatest interest to ourselves, the one we know best. It gravitates round the sun along an orbit traced at a mean distance of 143 million miles from the central luminary. Our Earth passes through its annual revolution at a distance of 92 million miles. There are, therefore, on an average, 51 million miles between the two orbits. On the night of my vigil, Mars happened to be at its minimum distance from the Earth. Fortunately, as the two orbits are neither circular nor parallel, the real distance is sometimes reduced to 37 million miles. Light, which takes 1⅓ second to traverse the distance between the Earth and the Moon, takes 200 seconds, or 3 minutes 20 seconds, to cross the celestial abyss which separates Mars from the Earth, It seemed to me that I really spent those 3 minutes in flying the distance, and I entirely forgot the high window of my Venetian palace over the aspect of the new world to which the flight of my thought had brought me. (2) THIRTY-SEVEN MILLION MILES PROM THE EARTH It is not very far, astronomically speaking. It is, in fact, quite near, a few paces away. The world of Mars is the first station of the solar system, the first planet we meet on leaving the Earth to visit the remote regions of the heavens. The farther we move away from the Earth, the smaller grows the apparent size of our own world. Seen from the Moon, our planet hangs in the sky like an enormous moon, four times the size of our own satellite, and sixteen times as luminous, for it is isolated in space and reflects the light received from the Sun, as is done by the Moon and the various planets of the solar system. From about 250,000 miles, therefore, the Earth still appears of a considerable size, being about four times the size of the full Moon. At 2½ million miles it appears ten times smaller in diameter, but still shows a perceptible disc. At the distance of the orbit of Mars, at the time when the planets are in greatest proximity (37 million miles), the Earth no longer shows a sensible disc, but is still the biggest and brightest star in the entire heavens. The inhabitants of Mars, therefore, admire us as a brilliant star in the sky, showing aspects similar to those which Venus shows to us. We are their morning and evening star, and no doubt their mythology has erected altars to us.