The Rosetta probe around comet 67P/Churyumov-Gerasimenko ( 67P ) reveals an anisotropic dust distribution of the inner coma with jet-like structures .
The physical processes leading to jet formation are under debate , with most models for cometary activity focusing on localised emission sources , such as cliffs or terraced regions .
Here we suggest , by correlating high-resolution simulations of the dust environment around 67P with observations , that the anisotropy and the background dust density of 67P originate from dust released across the entire sunlit surface of the nucleus rather than from few isolated sources .
We trace back trajectories from coma regions with high local dust density in space to the non-spherical nucleus and identify two mechanisms of jet formation : areas with local concavity in either two dimensions or only one .
Pits and craters are examples of the first case , the neck region of the bilobed nucleus of 67P for the latter one .
The conjunction of multiple sources in addition to dust released from all other sunlit areas results in a high correlation coefficient ( \sim 0.8 ) of the predictions with observations during a complete diurnal rotation period of 67P .