Television is ephemeral, a fact that some will find reassuring. But earthlings will continue to pump the kilowatts into the ether. And eventually, when those signals have washed over a few hundred thousand star systems, someone may notice.

Thanks to the fact that the Earth isn't a perfect sphere, and invoking a bunch of Newtonian physics, you can deduce that our planet wobbles, too, taking roughly 26,000 years to trace out a small circle on the sky, a phenomenon known as precession.

Note to academics: Aristarchus' track record of astronomical research would probably have guaranteed him tenure somewhere, if tenure had been invented. His stack of reprints included measuring the distances of the Moon and Sun.

Seth Shostak Quotes