What's the Latest Development?
A black pebble is the first-ever piece of a comet nucleus discovered on Earth, say a team of scientists led by Jan Kramers of the University of Johannesberg. The pebble is also studded with diamonds, which makes sense considering its origins: "Normally [diamonds] form deep in the Earth, where the pressure is high, but you can also generate very high pressure with shock. Part of the comet impacted, and the shock of the impact produced the diamonds." That impact, which took place about 28 million years ago over Egypt, also created large amounts of yellow silica glass across 6,000 square kilometers of the Sahara. A study detailing the research will appear in a forthcoming issue of Earth and Planetary Science Letters.
What's the Big Idea?
Scientists are fairly certain that comets have struck Earth before, but until now the only evidence existed in dust particles embedded in Antarctic ice and floating in the upper atmosphere. Because comets were created when the solar system first formed, the pebble -- named Hypatia in honor of the ancient Egyptian astronomer and philosopher -- will provide a great deal of scientific information about that time in astronomical history at significantly less expense than going up into space and collecting comet material, says Kramers.
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