What is this shadow on the moon?

[Penguin Pete]

I took these two photos at 7.51 and 7.52pm on the 1st of Jan (testing prime focus on new scope) and later noticed a shadow towards the lower right, moving left and down. The next photo I took 4 or 5 mins later had no shadow. This was the day after the partial eclipse. I don't think there was anything on the lens. Any idea what it could be from?

[jgs001]

I'd guess at some thin cloud, I was doing some imaging on the moon that night, and kept getting that happen to me.

[barkis]

There was a partial Lunar Eclipse on Dec.31-Jan.1st., but it was all over by the time you took your pictures, otherwise you may have caught earth's penumbral shadow leaving the lunar surface.

No chance of it being that though.

Johns explanation is the likely answer.

Ron.

[MoonNut]

Yep, looks like cloud to me too (and I spend a lot of time looking at the moon) and you say it was gone 5 mins later.

Nicely captured though!

[Penguin Pete]

Thanks everyone. I hadn't thought of clouds but that could make sense.

[Akula]

Can i ask what magnification this was ??