Those were the questions that throbbed through our brains now as our hurtling space-flier shot on and on, Neptune growing with each hour before us. By the nineteenth day its disk had expanded to such a degree that we were able to discern upon it the cloud-belts that had already long been seen upon it by Earth's astronomers. By the twentieth those great vapor-belts were plainly perceptible, and also Triton, its moon, had become visible to our unaided eyes, revolving close about the great planet in its sharp-slanted plane, being now behind the planet but so much above it as to be completely visible to us. By the twentieth, too, the sun behind us had become hardly more than a super-brilliant star, its tiny fiery disk bathing us still with a certain amount of light, although long before this we had ceased to rely upon its heat on our flier's sunward side and had had recourse to our own heating-mechanism. By this time too, of all the planets, only Jupiter and Saturn were visible behind us; the rest were invisible to us at the colossal distances which now separated us from then. It was not behind but ahead, though, that we were gazing, as our space-flier flashed over the last portion of its great trip, as Neptune apparently grew in size before us. Seated in my control-chair, with Whitely and Marlin and Randall in their chairs beside me, I watched the mighty planet fascinated, as we hurtled on toward it in the early hours of the twenty-first day, that day that we had calculated would bring us to our goal. And truly, now, Neptune was looming in something of its true greatness before us. Only a tiny point of light in a telescope on Earth, hardly more than that on the long days of our journey outward, we saw it now in some size and splendor, a huge cloud-belted world as large almost exactly as Uranus, outrivaled in the solar system only by it and by the two giants of Jupiter and Saturn. Over sixty times larger than our own Earth it was, a huge world spinning far out here at the solar system's very edge, the last outpost of that solar system with beyond it only the awful emptiness of interstellar space. Silently we gazed toward its great, green disk, its small gleaming moon, as our space-flier throbbed on toward it. Whitely, as usual, was checking from time to time the performance of the never-ceasing generators whose great force-ray, pressing against Saturn still, was hurling us forward. Randall was gazing forward with me, helping me now and then to ascertain from our speed and distance dials our distance from the great planet. Marlin had applied himself to the telescope, was gazing ahead through it toward the big world's cloud-wreathed surface, touching a focusing wheel now and then. For minutes we throbbed on thus, the beat of the generators the only sound in the hurtling space-flier's interior, but at last Marlin drew back from the telescope's eye-piece and frowned as he gazed toward the great green planet ahead.