Free Sky's Dark Labyrinth by Stuart Clark Page A

would be possible to build a shield to bounce the celestial forces back into space – though only the ruinous ones, of course. Perhaps roofs could be made in this way and people could wear protective hats to banish illness …
    Longomontanus called out an observation from the other side of the sextant, startling Kepler, who asked for it to be repeated and then fought the numbing ache in his fingers to record the figures. But the act felt meaningless, like collecting raindrops instead of swimming in the ocean. Any literate person could do this work, but only he could solve the shape of the Martian orbit.
    In his head, he tried juggling the planet’s observations. He had been shown so few that he had memorised them easily, despite the fever.Now, he could rearrange them at will and search for their hidden meaning.
    â€˜Johannes, I’m talking to you,’ Longomontanus hissed. The assistants never raised their voices on the roof. It was as if they feared alerting the stars to their vigil. ‘Declination: thirty-four degrees, twenty-five arcminutes.’
    â€˜It’s no good,’ Kepler said, letting his arm fall to his side, all pretence of standing with the notebook at the ready forgotten. ‘When did an architect ever lay the stones himself?’
    Longomontanus unbent himself from the instrument and pressed his hands into the small of his back. ‘You misunderstand. In Tycho’s castle we are cogs, not wheels.’
    â€˜I’m sorry. I have to go and work.’ He did not wait for an answer but thrust the notebook at his companion and dodged the other instruments and assistants on his way to the stairway.
    A few sparse torches lit the corridor beneath. As Kepler threaded his way from one pool of shivering brightness to the next, he heard the sound of hushed voices, some way ahead. The urgency of their tone halted him, and he sank into the shadows.
    It was Tengnagel and Elisabeth, Tycho’s eldest daughter. They were whispering and pawing each other. Tengnagel seized her by the arm and drew her close, pressing his mouth against hers.
    Caught between disgust and fascination, Kepler watched the urgent fumbling of their hands upon each other. As their kissing reached its crescendo, she pushed him away and giggled breathlessly before slipping through a doorway. Kepler knew that he should move before he was discovered. Inadvertently his feet shuffled on the gritty stone.
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    Tengnagel was on the verge of following Elisabeth inside when the noise caught his attention. ‘Who’s there?’
    Kepler flattened himself against the dark wall.
    Tengnagel challenged again, this time drawing a small sword.
    At the sight of the blade, Kepler stepped into the orange light and locked eyes with the younger man. Wordlessly Tengnagel sheathed his sword, reached for Elisabeth’s door and pulled it shut. Turning on his heels, he marched away, tossing his hair.
    Once safely inside his room, Kepler wrote out the memorised observations of Mars. Individually each coordinate held a glimmer of meaning; taken together they were loaded with significance.
    They were the coordinates of Mars for the planet’s last ten oppositions . During an opposition – according to Copernicus – Earth caught up with Mars and lapped it like an Olympian on an inside track. When this happened, every 780 days, Mars appeared to backtrack in the sky before resuming its onward motion.
    Kepler toyed with the numbers, deciding on the best way to attack them tonight. At opposition Earth and Mars were at their closest, with the Sun banished to the opposite side of the sky. So, these figures provided excellent starting points for his analysis. Yet, without the observations in between, all he really possessed were a few guard towers but no walls from which to build a citadel. Nonetheless, it was a start.
    Longomontanus arrived as the sky began to blush with the dawn. His movements were laboured, more