Space exploration history is happening today as the Rosetta spacecraft arrives at a comet as it orbits the Sun.
It's the first close, extended examination of a comet, and will include deploying a lander to the comet's surface.
The European Space Agency, with an assist from NASA, launched Rosetta on its four-billion mile mission ten years ago. Live online coverage of the Rosetta mission is available at rosetta.esa.int.
(Photo: Handout / 2014 ESA)