In regard to Maik's post about anti-tails, now might be an
appropriate time to mention 2P/Encke's anti-tail, or as it is more
commonly referred to in the literature, its "sunward fan".

While certainly not seen at every apparition, a few of the CCD images
of the past week decidely suggest it may well become a feature of the
current return. These images are recording a very faint extension
toward PA 330* or so, while any normal tail should point roughly
toward PA 180* currently.

When P/Encke's "sunward fan" feature displays itself, the coma takes
on an extended, generally parabolic or hyperbolic shape, opening
sunward. The central condensation or nucleus is displaced
dramatically anti-solar within the coma at such times. In addition,
on a few rare occasions, a nebulous "tube" or ribbon of light, a
considerable fraction of the coma's diameter is width, may also be
seen directed sunward for a distance greater than the extent of the
coma. I saw this latter feature distinctly during P/Encke's 1980
apparition near T-50 days, much to my amazement. As I recall, once
during the 19th century this bizarre feature extened several degrees
sunward!

2P/Encke will probably have to reach about m1=10 before the sunward
fan will become obvious visually, so we may be talking about right
around full moon next month (but remember the total eclipse!). CCD
imagining seems to deal much better with moonlight than do visual
observers, so I'd watch for signs of the fan to become obvious there
first.

John Bortle