In The Time of Dinosaurs

<The comet bothered you? But not the flash of light?>
"Lightning. So what?"
<No, no. Not lightning. I assumed you knew. It was artificial in origin, not natural.>
It took me about five more steps before I said, "What?" I stopped. Jake stopped. Cassie stopped.
"Artificial?" Jake asked. "What do you mean, artificial? Doesn't that mean man-made? Or at least, made?"
<Yes, of course. The flash was not a naturally occurring phenomenon. It was all wrong for lightning. My stalk eyes are capable of seeing a little further into the ultraviolet and infrared spectra of light and ->
"Just tell us what it was!" Cassie yelled impatiently. That shocked us all. Cassie never yells. But then again, maybe she's just not a morning person.
<I believe it was an explosion. I would have thought it was a Dracon beam striking a target, only it was too blue.>

[...]


"Ax-man, I think maybe you're just nuts."
<Me? Wrong? It is possible,> Ax said dubiously. <But the nature of the light certainly seemed to . . .>
He droned on for a while about the wavelengths and the retinal impact patterns and distance-sense and a lot of other Andalite stuff that humans would probably learn about someday.