Deep Impact

On the morning of October 22, 1993, local time, the visitor hit the top of the atmosphere over Ellsworth Land in Antarctica. It pierced the sky in a flash of light, moving a hundred times faster than a meteor, passing from the thinnest air and into the ice in a fraction of a second. It cut through the rock below with equal ease, flying through the solid earth in a northeasterly direction. In less than 20 seconds, it had crossed the South Atlantic, deep beneath the ocean floor. When it passed below the southern tip of Africa, it was more or less halfway between Cape Town and the center of Earth. That was as deep as its straight path through the planet would take it; from then on it headed up. Fifteen seconds later, 6,000 kilometers across the Indian Ocean from Cape Town, it left Earths crust somewhere between Sri Lanka and Thailand. It lanced up through the afternoon sky and headed back out to the stars. The whole visit lasted less than a minute, and nobody saw a thing.
http://www.wired.com/wired/archive/11.02/matter.html