We're seeing this as a globular cloud, because the tail of the receding comet happens to point away from the Earth. But cocmets can have two tails, one dusty and straight while the other is charged (?) and curved.
A curved tail would be visible, I presume as a pear-shaped extension of the cloud but it isn't there. What does this tell us about Holmes? Or rather, what is known about comets that have, or don't have, curved tails?

John