The European spacecraft Rosetta has become the first ever to catch up with a comet.

It is a landmark step in a decade-long mission that scientists hope will help unlock some of the secrets of the solar system.

Rosetta will accompany comet 67P/Churymov-Gerasimenko on its trip around the sun and land a probe on it later this year in an unprecedented manoeuvre.

As it neared the comet, Rosetta took pictures revealing that it is not shaped, as had been assumed, like a rugby ball or American football but rather comprises two segments, connected by a neck.

Scientists hope data the probe gathers on the surface of the comet will allow them to peek into a kind of astronomical time capsule that has preserved for millions of years clues about what the world looked like when our solar system was born.