When light pollution first was raised as an issue, it seemed a jest, an effete-tree-hugger crusade. All that artificial light isn't toxic ... is it?

I was witness to epiphany -- someone else's. At the end of a rugged day on a forest fire in Colorado, I should've been snuggled in a sleeping bag, but was distracted. Our camp sprawled in a high, remote meadow. The Milky Way was dense and bright, like a sun-drenched cloud. Stars seemed poised at the ridge crests, almost in touch. After dusk I strolled beyond a pool of lantern light into the glare of the galaxy. I stared at the sky, unwilling to surrender to sleep.

On the second night I was trailed by Y.T., a Vietnam veteran who over the prior two days had related horrifying, mesmerizing tales. He'd seen everything, but not the night sky, not like this. When he asked what I was looking at, I pointed. There was M31, the Andromeda Galaxy, a faint patch of light visible with the naked eye, a maelstrom of 1 trillion suns, and two-and-a-half-million light years away. That steered us into talk of cosmic distance and time -- we were seeing Andromeda as it was when homo sapiens did not exist.

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