Frank Drake's famous equation helps to quantify our chance of finding ETs — or at least to pose the essential questions.

Several big hunts are seeking radio and laser emissions from other civilizations among the stars. From the Allen Telescope Array to SETI@home, here's a rundown of all current and recent searches.

Searches for extraterrestrial intelligence are about to expand into new realms, thanks to new advances in technology — and new thinking.

SETI researchers have long had to beg time on instruments built for conventional radio astronomy. Now they've built one of their own.

Why the world's biggest search should reverse its strategy — and why the first signal we hear will probably come from an extremely powerful civilization extremely far away.

The world's largest optical SETI telescope begins sweeping millions of stars for laser signals from alien civilizations.

It seems unlikely that life could arise on giant, gaseous exoplanets. But what about their moons?

Searchers for extraterrestrial intelligence reach a humble conclusion: we don't know what we don't know.