Peter,

That is a good image of the anti-tail.

The normal reason for this is that we are seeing dust that has been
spread around the comet's orbit. This is the dust that would lead to an
annual meteor shower if it intersected the Earth's orbit. The effect is
normally only seen when the Earth is close to the comet's orbital plane
since we then see the dust edge-on. Since 67P is in a low inclination
orbit and is near to perihelion we are not far from that situation now.

The most famous of these anti-tail spikes was C/1956 R1 (Arend-Roland)
but there have been many more recent examples.

Nick.

On 11/11/2021 19:57, Peter Carson wrote:
> Here’s an image of 67P/Churyumov-Gerasimenko taken on the Nov 10^th from my
> remote observatory. I’ve highly contrast stretched and inverted it to show what
> appears to be a faint anti-tail. I’ve recently seen some similar images and
> thought the anti-tail might be an artefact, but it’s not.
>
> Can someone tell me what we are seeing?
>
> My image has a FOV of 48’ wide. A larger FOV and longer exposure is required to
> better see what is going on. Other details on the image.
>
> Peter
>
> Peter Carson
>
> Essex UK
>
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