Tune-in to PBS at 9pm tonight to watch NOVA's latest episode about a mysterious machine found buried on the sea floor. Discovered off the coast of a tiny Mediterranean Island inside a 2000-year old shipwreck, the Antikythera Mechanism is widely-believed to be the world's first computer. Badly corroded by seawater, its true purpose has only been revealed through the use of X-rays and other hi-tech imaging devices. Watch the sneak preview below where researchers Tony Freeth and Alexander Jones explain how they deciphered the cryptic messages etched into the machine's gears. They tell us this remarkable device might have accurately predicted eclipses--down to the very hour they occurred.