http://www.slate.com/blogs/bad_astronomy/2014/12/16/rosetta_s_comet_grey_but_hardly_dull.html
Dec 17, 2014 #1 TomTerrific Well-Known Member Rating - 0% 0 0 0 Jul 11, 2010 4,061 38 Centre, Ky http://www.slate.com/blogs/bad_astronomy/2014/12/16/rosetta_s_comet_grey_but_hardly_dull.html