Earliest Known Comet to Strike Earth

Introduction

Scientists have discovered evidence of the earliest known comet to strike Earth. The event occurred 28 million years ago when the comet entered the atmosphere over what is now Egypt, got heated and exploded, resulting in the formation of yellow silica glass. The glass fell over a 6,000 sq km area in the Sahara. A specimen of the glass can be found in Tutankhamun’s brooch. The impact also produced microscopic diamonds. The clue came from a black pebble found years ago by an Egyptian geologist in the area. Research on the pebble led to the conclusion that it came from a comet. Finding comet material is very rare and space agencies invest billions to collect a few micrograms of such material from space. Comet fragments have never been found on earth except in microscopic sizes. The discovery provides an opportunity to study the comet material and could give invaluable information regarding the creation of the solar system. 

Source

Down To Earth, November 2013