To explain a cometary coma Wikipedia make use of one of
I am very proud that Mr.Hawking personally requested
Astrophotography by the Masters/by Robert Gendler.
Astronomy Magazine September 2008
A lot of links on the NASA website are pointing to my website
Springer Wien/New York
Several images of comet Machholz C/2004 Q2 which I have taken
Our base ground images of comet 73P/SW3 are compared to Hubble images
Astrophotography under the dark sky of Namibia.
The Most Awesome and Inspiring Images of the Heavens