What is a comet antitail?

This diagram shows the geometry of a comet tail and antitail.

Specials thanks to Ray Brooks for his help in foud tails and antitails and to Wolf Peter Hartmann for his mails and distribution of the drawing!

Cool links, about Lulin antitail:

Planetary Society Emily's blog (USA)

Astro Picture Of the Day (USA)
Malaciencia (Spain)

Spaceweather (USA)

El Cielo del Mes (Spain)

Regensburg observatory (Germany)
Crystal's blog (China)

Space News (Japan)
PGJ Astronomie (France)