"[opening lines] No one would have believed, in the middle of the 20th century, that human affairs were being watched keenly and closely by intelligences greater than man's. Yet, across the gulf of space on the planet Mars, intellects vast and cool and unsympathetic regarded our Earth with envious eyes, slowly and surely drawing their plans against us. Mars is more than 140 million miles from the sun, and for centuries it has been in the last stages of exhaustion. At night, temperatures drop far below zero even at its equator. The inhabitants of this dying planet looked across space with instruments and intelligences of which we have scarcely dreamed, searching for another world to which they could migrate. They could not go to Pluto, outermost of all the planets, so cold that its atmosphere lies frozen on its surface. They couldn't go to Neptune or Uranus, twin worlds in eternal night and perpetual cold, both surrounded by an unbreathable atmosphere of methane gas and ammonia vapor. The Martians considered Saturn, an attractive world with its many moons and beautiful rings of cosmic dust, but its temperature is close to 270 degrees below zero, and ice lies 15,000 miles deep on its surface. Their nearest world was giant Jupiter, where there are titanic cliffs of lava and ice with hydrogen flaming at the tops, where the atmospheric pressure is terrible - thousands of pounds to the square inch. They couldn't go there. Nor could they go to Mercury, nearest planet to the sun; it has no air, and the temperature at its equator is that of molten lead. Of all the worlds that the intelligences on Mars could see and study, only our own warm Earth was green with vegetation, bright with water, and possessed a cloudy atmosphere eloquent of fertility. It did not occur to mankind that a swift fate might be hanging over us, or that from the blackness of outer space we were being scrutinized and studied – until the time of our nearest approach to the orbit of Mars during a pleasant summer season."