Today the European Space Agency's Rosetta probe landed a robot onto comet 67P/Churyumov-Gerasimenko, which is currently hurtling through our solar system more than 300 million miles away from Earth. Vox science writer Joseph Stromberg explains Rosetta's journey, and why we would want to land on a comet in the first place.
Further reading: Scientists just landed a spacecraft on a comet for the first time. Here's why it matters.
