Hi folks,

A while back, I corresponded a bit with a gent who suggested that,
while the ion trail can be safely modelled as pointing in the anti-solar
direction (which is what Guide does), the dust trail can be modelled
as running in the line of variation (that is, the dust stays in the
same orbit as the comet, but runs a little "behind" it, with the
smaller particles getting lifted a bit in the antisolar direction.)

If you click on a comet, then on "Display", then "Options",
you'll see there is an option to turn on display of the line of
variation. Turn that on, and set it to (say) a 1-day length, and
click OK; you'll see that the LOV does indeed run at a position
angle of about ten degrees.

-- Bill