Inside #Rosetta’s #comet
▻http://blogs.esa.int/rosetta/2016/02/04/inside-rosettas-comet
This article is mirrored from the main ESA Web Portal. There are no large caverns inside #Comet_67P/Churyumov-Gerasimenko. ESA’s #rosetta mission has made measurements that clearly demonstrate this, solving a long-standing mystery. #Comets are the icy remnants left over from the formation of the planets 4.6 billion years ago. A total of eight comets have now been visited by spacecraft and, thanks to these missions, we have built up a picture of the basic properties of these cosmic time capsules. While some questions have been answered, others have been raised. Comets are known to be a mixture of #dust and ice, and if fully compact, they would be heavier than water. However, previous measurements have shown that some of them have extremely low densities, much lower than that of water ice. (...)