The Rosetta spacecraft and its comet just hit a major milestone

The Rosetta mission can start to cool down now.

August 13, 2015 will go down in the books as the first time a spacecraft has accompanied a comet past the closest point it'll ever get to the sun while in orbit.

This spacecraft is the European Space Agency's Rosetta satellite, and right now it's in orbit aroundComet 67P/Churyumov-Gerasimenko — one of the more than 4,000 known comets in the solar system. The Rosetta mission also has a lander on the comet's surface.

The mission's helping us understand Comet 67P better than any other comet.

Here's a recap of the heroic mission, what it has taught us so far, and what we still hope to learn:

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Here is a selfie of the Rosetta spacecraft in orbit around Comet 67P, shown in the background. Rosetta was launched in 2004 and spent 10 years in space catching up to the comet. When it arrived, scientists were shocked by the space rock's bizarre double-lobed shape.

Here you can see jets that the comet is ejecting as ice turns to a gas in the vacuum of outer space. Comet 67P is expected to get more active as it approaches the sun with increasingly more jets spewing off the surface.

This is the first picture that the camera on Rosetta took of Comet 67P after starting to orbit it on August 6, 2014. The spacecraft is about 60 miles above the comet's surface in this brilliant shot.

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