Those thoughts had led to more tossing and turning—if those were the right words for not being able to sleep in a loose sack in zero gravity—as he had wrestled with the question of "When?" Predicting it on Day 720, plus or minus a few, had been all well and good back on Day 360. But Day 700 was now approaching its end, and the "plus or minus" thing was seriously bothering him. Lately they’d narrowed it down to "plus or minus three days," but that was in response to political pressure. It wasn’t a legit scientific move. And it meant something different to scientists. Laypersons understood it as "certainly between 717 and 723." Scientists would instead say that if you could repeat the experiment of blowing up the moon a large number of times, and keep track of the time-to-White-Sky separately in each case, the numbers would fall into a normal distribution, a bell-shaped curve, with about two-thirds of the instances falling within that range.