I learnt a new word this week. It is not a poetic word, not one that rolls off the tongue or finds its way easily into a sentence. It sounds more like something you would scrape off a laboratory bench. The word is passivation. I came to it by way of the western sky. Last weekend, just after sunset, I saw something that did not belong. A bright, shifting cloud was moving steadily above the Rock and Pillar Range. Not drifting, as clouds do, but travelling with purpose. It had a faint internal glow, as if lit from within and it changed shape as I watched. For a moment, it felt nearly alive, which is usually a sign that it is not. My first thought was rockets. Ten years ago, that would have seemed an extravagant guess. Now it is almost the default explanation. We have grown used to strange apparitions: spirals, plumes, luminous threads stretching across the dark. The sky has acquired a new kind of traffic.…