How comets are born / Rosetta / Space Science / Our Activities / ESA
http://www.esa.int/Our_Activities/Space_Science/Rosetta/How_comets_are_born
Detailed analysis of data collected by Rosetta show that comets are the ancient leftovers of early Solar System formation,
and not younger fragments resulting from subsequent collisions between other, larger bodies.
Understanding how and when objects like Comet 67P/Churyumov–Gerasimenko took shape is of utmost importance in determining
how exactly they can be used to interpret the formation and early evolution of our Solar System.
A new study addressing this question led by Björn Davidsson of the Jet Propulsion Laboratory, California Institute of
Technology in Pasadena (USA), has been published in Astronomy & Astrophysics.