Join Exploratorium scientist Paul Doherty as he illuminates the primitive objects under investigation by NASA's Rosetta Mission—comets, icy leftovers from the formation of our solar system over 4.6 billion years ago. The chemical composition of comets has hardly changed since their formation, and so they carry essential information about the origins of life on Earth.

The European Space Agency’s comet-chasing spacecraft was the first to undertake a lengthy, close-up exploration of a comet. Rosetta, which orbited and then deployed a lander on Comet 67P/Churyumov-Gerasimenko in 2014, helped scientists reconstruct the history of Earth and its neighbors in our solar system. After entering the comet’s orbit, Rosetta released its Philae lander onto the icy nucleus, where it sent photographs and other data back to scientists for detailed study.