Crater perspectives

Comments and questions about the APOD on the main view screen.
Neophyte
Asternaut
Posts: 1
Joined: Sun Sep 25, 2005 5:11 am

Crater perspectives

Post by Neophyte » Tue Sep 27, 2005 3:56 am

Why, when I look at photos of a body covered in craters, such as the recent one on APOD of Enceladus, do the craters seem to change perspective between being concave and convex?

FieryIce
Science Officer
Posts: 334
Joined: Thu Jul 21, 2005 3:06 pm
Location: Vancouver Island, BC

Post by FieryIce » Tue Sep 27, 2005 2:50 pm

I sometimes have the same problem; it is to do with optics. You can stare at the image and see the crater as concave or convex but by noting the shadowing of the overall image will clue you as to concave or convex.
Tic Toc

Wayne
Ensign
Posts: 77
Joined: Tue Apr 12, 2005 10:27 am
Location: UK

Post by Wayne » Wed Sep 28, 2005 12:55 am

It's lighting and perception.

We're used to seeing lighting from above and indeed our brains are hardwired to interpret unknown lighting as being from above, since the sun is never below the observer in normal circumstances.

Simply flip the image 180 degrees and you'll see concave craters.