For the first time, scientists have spotted large patches of water ice on the surface of a comet, thanks to instruments aboard the European Space Agency’s Rosetta orbiter.

The finding in Nature solves a mystery about water ice in comets. Scientists already knew that the coma — the expansive cloud of gas surrounding the comet’s nucleus — is dominated by water molecules. They also knew that water ice is one of the main components of the nucleus. But until now, traces of water ice on the surface of the comet had been difficult to detect.

“First, not finding ice was a surprise; now, finding it is a surprise,” said Murthy Gudipati a planetary scientist at the Jet Propulsion Laboratory and an author on the paper. “It is exciting because now we are starting to understand the upper dynamic layers of the comet and how they evolved.”

The surface water ice on comet 67P Churyumov-Gerasimenko was discovered in two places several tens of feet across in a region known as Imhotep. In both cases the ice appeared on cliff walls and debris falls.

 

The answer to dinosaurs frills?

Scientists believe they’ve figured out why some dinosaurs had cumbersome horns and frills: to attract mates.

The data offer support for the theory “that these features were under selection as socio-sexual dominance signals,” concluded researchers from Queen Mary University of London, who published their findings in the journal Palaeontologia Electronica. Scientists found that the frills on specimens of Protoceratops andrewsi, which belong to the same group as the triceratops, grew disproportionately larger to their bodies and wider as they got older, suggesting the frills served a function only adults would need — such as signaling to a mate. But it is by no means a settled question.

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