Today, the European Space Agency announced that its Rosetta mission successfully arrived at comet 67P/Churyumov-Gerasimenko after a 10-year journey. As the probe approached over the past several weeks, it provided greater detail on the oddly shaped comet, which was venting water as its orbit drew it closer to the Sun. Now, at just 100km from the comet's surface, Rosetta is providing detailed images of a truly otherworldly landscape.

67P/Churyumov-Gerasimenko occupies an elliptical orbit that takes it from areas beyond Jupiter to somewhere in between Earth and Mars (currently, it's midway between Jupiter and Mars). That presents a significant challenge, since any probe intended to track the comet must roughly match its orbit before approaching—or it would need a prohibitive volume of propellant to slow down. This explains Rosetta's 10-year journey, which included four orbital flybys of Earth and Mars to put it in place for a gradual approach.

Earlier this year, Rosetta successfully woke from hibernation, and it's been imaging the comet during its approach. Early images indicated that 67P/Churyumov-Gerasimenko has a two-lobed structure that some have compared to a rubber duck, albeit one with an unusually large head. The second lobe, corresponding to the duck's body, is broader and more oblong.

Since the initial approach, Rosetta has eased to within 100km of the comet's surface and captured detailed images of a very foreign world, one by turns smooth and pockmarked. The comet has been seen spraying a tiny bit of water into space (estimates are 300ml a second, based on Rosetta images), but the complex surface of 67P/Churyumov-Gerasimenko suggests a correspondingly complex history of activity. The comet is currently heading closer to the Sun, which may increase this venting over time.

The plan for the coming weeks is to have the orbiter approach to a distance of 50km before entering a circular orbit at a distance of 30km. Over the coming month, it will search for potential landing spots for Philae, a package of instruments that will tether itself to the comet's surface. The lander is expected to reach the surface of 67P/Churyumov–Gerasimenko in early November.

For now, however, you can appreciate these images that have been generated during Rosetta's journeys.