An unusual Moon

[andrew s]

While tidying up I came across this picture of the moon I got on a visit to the Lick Observatory. 

Can you spot what they have done.

Regards Andrew 

[Cornelius Varley]

4 minutes ago, andrew s said:

Can you spot what they have done.

Yes, but I'm not saying..

[laudropb]

I  have seen similar ones before.... I think. I let others ponder on it.

[andrew s]

Just to be clear no digital trickery was used.

Regards Andrew 

[lenscap]

Have they stitched 1st quarter and 3rd quarter images together so that the central area appears as it does when near the terminator?

[JamesF]

Just now, lenscap said:

Have they stitched 1st quarter and 3rd quarter images together so that the central area appears as it does when near the terminator?

It looks like that to me.  The craters to the west of the centreline have a shadow on the western side of the crater whilst those on the east have the shadow on the eastern side, and near both limbs there are no shadows at all, suggesting illumination from the sides.  One or two of the craters in the centre even look as though they're in shadow from both sides :)  So I'd assume the two images blended together, as you say.

James

[Gina]

Can see the join!

[andrew s]

54 minutes ago, lenscap said:

Have they stitched 1st quarter and 3rd quarter images together so that the central area appears as it does when near the terminator?

Quite right, but it was done before digital technology. The photos were from the 36" refractor.  A very impressive bit of engineering.

Regards Andrew 

[andrew s]

Maybe a challenge for  modern observers would be to do a mosaic with close to optimal lighting across the whole face?

Regards Andrew