> If it were deliberately manufactured by a sentient alien civilization, why choose that specific shape? A light sail based probe doesn’t seem to be a sufficie

> If it were deliberately manufactured by a sentient alien civilization, why choose that specific shape? A light sail based probe doesn’t seem to be a sufficient enough explanation for the shape. Why not? Assuming a civilization is (or was) technologically advanced enough, they would probably be doing lots of things we couldn't understand, especially given how little we know about this thing. He wasn't saying it was definitely, or even probably, a light sail, just that we should entertain the possibility. Besides, we don't actually know what the shape is, only that its changes in brightness would be consistent with an elongated object, which is the simplest explanation. Or, maybe the object is perfectly spherical but the brightness changes are due to seeing a light sail at different angles, which is extremely unlikely but within the realm of possibility.