Remnant of a Comet

摘要

A black, diamond-spackled pebble just a few centimeters across is the remainder of a comet that struck Earth almost 29 million years ago-making it the first direct evidence of a comet exploding in our atmosphere, scientists say. The stone, named "Hypa-tia" after an Alexandrine mathematician and philosopher, was found in 1996 among bits of yellow sand glass (also known as the Libyan Desert Glass) scattered across tens of kilometers in southwestern Egypt, near the border with Libya. The glass itself has been dated to 28.5 million years and has long been thought to be the result of a meteorite impact or an airburst caused by a comet breaking up in Earth's atmosphere.