Russ was carried away with the possibilities. "This hints at great things, Burl. Out near Pluto, where the system is even colder, there may be other forms of this frigi-plasmic life, if I may coin a word. This means a whole new science!" They returned to the ship with their astonishing news. The _Magellan_ slowly skimmed over the surface of Oberon. They found whole forests of this glassy frigid vegetation, but not much evidence of any animal life larger than the creature the two explorers had seen. Over the Sun-tap station--a ringed layout like the others, whose cluster of masts caught the emanations of the distant Sun on the one hand and directed them outward to the still unseen planet Pluto on the other--the ship halted. It drew up fifty miles, pointed its tail and blasted forth a rocket-driven, tactical atomic bomb. The blast on Oberon was tiny compared to the one which had devastated Iapetus, but it still left a deep indentation in the surface for future space fliers to see. They left it and the Uranian orbit behind them and headed outward once again. Behind them now lay the worlds of the Sun's family, while far off to one side lay the tiny light of Neptune. Ahead, between them and the vast gulf of interstellar space, lay only the dark, mysterious ninth planet, the enigmatic world named after the lord of the underworld, Pluto. The _Magellan_ plunged on, in constant acceleration, moving outward to the farthest limit of the solar system. They had traveled almost one billion, eight hundred million miles from the Sun--and yet they still had two billion miles more to go. This was the longest stretch--and during it, they would reach speeds greater than any they had touched before. They shot outward, faster and faster, eating up the infinite emptiness of space, driving the vast stretch that divided Pluto from its neighbors. The Sun, already small, dwindled steadily. It was still the brightest star in their sky--of all the stars, it alone retained a disclike shape, and the faint flicker of its coronal flames could occasionally be made out--but it no longer dominated the heavens. To find the Sun, they now had to look for it as they would for any other star. As for Earth, it could not be seen. So close to the tiny Sun it lay that only their sharpest telescopes could bring it out. Even Jupiter showed up only as a thin, tiny crescent near the solar point of light. "Pluto's a mysterious world," said Burl as he and Russ scanned the heavens for a first glimpse of it. "The accounts in your astronomy books give very little real information on it--but what they give is strange. They say it's the only planet beyond Mars that is a small solid world like the inner ones. It seems to be the same size as Earth--not at all like the big outer worlds. And they say it seems to be the same mass as Earth--a solid world whose surface gravity would be the same as our own planet's."