Read Online Destroyer of Worlds by Larry Niven - Free Book Online

a term as any for the final possibility: something altogether unexpected.
    She yawned again. “So, what are you reading?”
    Sigmund slid his comm unit toward her. “An Earth story from way before my time. Before spaceflight.”
    She blinked through a few pages and handed back the comm. “When you finish, let me know if you recommend it.”
    â€œWill do.” Sigmund found Kirsten had lost his place. “Jeeves, I was coming up to an eclipse reference.”
    Some invisible handshake between AI and his portable unit did the trick. Sigmund resumed where he had left off. What had he been reading?
    A nineteenth-century time traveler fancifully thrown back to medieval England, condemned as a witch. He avoids getting burned at the stake (ugh!) by using his foreknowledge of the imminent eclipse to claim power over the sun. How very convenient, Sigmund thought—
    â€œFinagle!” he blurted.
    Kirsten looked up from her tea. “Sigmund?”
    â€œI may need you to do some math for me.” A few taps put his comm’s touchpad into drawing mode. He sketched a solar eclipse: sun, moon, Earth. Free-flying worlds don’t experience eclipses.
    â€œThe sun is a yellow star,” he began. That was not only Sigmund’s questionable memory talking; New Terran biologists concurred. Human eyes were optimized for such a sun. So were plants grown directly from seeds in
Long Pass
’s dwindling collection. Earth-evolved crops cultivated on New Terra had already begun adapting to the more orange emissions of New Terra’s orbiting artificial suns. Those false stars radiated the light that Hearth’s biota preferred. The best estimate was that Earth’s sun had a surface temperature around ten thousand degrees—entirely ordinary. As a clue to Earth’s location, that inference was all but useless.
    Earth’s estimated year length was also entirely normal, putting the planet well within the habitable zone for a range of candidate stellar masses. Planetary orbital pa ram e ters were a function of solar mass, so even the decent guess Sigmund had at the length of Earth’s year said nothing definitive about the orbital radius.
    But now factor in
A Connecticut Yankee
’s total eclipse . . .
    Range of estimates for the apparent size from Earth of its sun. Twelve months—twelve orbits of a moon!—in a year. So how big is that moon to fully eclipse the sun?
    It depended how close to Earth that moon orbited.
    They needed a whole second set of approximations about Earth itself. New Terra had surface gravity Earth-like enough not to have seriously messed with Sigmund’s reflexes. Call Earth’s surface gravity New Terran, plus or minus a few percent. New Terra and the five worlds of the Fleet gave a range of densities for rocky, habitable worlds. Density and surface-gravity estimates together implied Earth’s mass, and so orbital pa ram e ters for its satellites.
    Jeeves collated estimates and crunched the numbers. Kirsten tweaked the program whenever Jeeves bogged down.
    The moon was, in a word, big. At
least
two thousand miles in diameter. Call it a quarter the diameter of Earth itself. A real clue, at last!
    â€œWe’re hardly looking for a world at all,” Kirsten said in awe. “Earth and its moon are nearly a double planet.”

9
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    Sigmund was hindmost for this mission, and the hindmost has prerogatives. Baedeker reluctantly admitted the human to his cabin.
    The main furnishings were a small synthesizer and mounds of pillows. Sigmund looked about and elected to remain standing. “Baedeker, you need to make peace with Eric. We’re a crew. We must all get to know each other, learn to trust each other.”
    Trust Eric? The man had hate in his heart. And when had a Citizen ever shared a spaceship with another species without being in charge?
    Still, the hindmost had his prerogatives. “I see your point, Sigmund. The