APOD Feb 3 2005 - shadows

Robert Rosen · Post by **Robert Rosen** » Thu Feb 03, 2005 3:26 pm

I have a question about the picture from February 3, 2005. It appears
as though all the shadows on the craters are on the right side.
However, the shadows on the uplift in the center the large crater is on the left side. Is this simply an illusion or is there a more complex solution?

makc · Post by **makc** » Thu Feb 03, 2005 3:30 pm

on APOD page, rjn wrote:Explanation: Stark shadows show off the central peaks and terraced walls of 120 kilometer wide Pythagoras Crater

Boldra · Post by **Boldra** » Thu Feb 03, 2005 3:52 pm

I don't see this, although apparently it's quite common. See this ESA write up.

http://www.esa.int/SPECIALS/SMART-1/SEMEPMO3E4E_0.html

cdenney · Post by **cdenney** » Thu Feb 03, 2005 8:45 pm

OK, so I see this picture of "craters" and I'm confused, cause it looks like bumps. So I download the picture by clicking on it, following the link shows a 90 degree cw rotation of the image. (still seeing bumps)
I load it into photoshop and rotate the image back to the original orientation and reverse the colors, tada now it looks like craters, but odd color. meh
D'oh! now I try horizontal flipping, and it works fine, as does a 180 degree rotation fro the original, or 90 deg cw from the file.

Now the cool part:
In one degree increments I rotate the image back ccw, I can get to about 45 degrees ccw before starting to lose the "craterness" of the objects in the picture. Then if I look away from, say, a 30 ccw rotation... bumpy again.
So my brain can be trained, a bit, to see it correctly. Might work better if I tried it with a printout.

It's like a one page optical illusions book.

I liked the esa link too, thanks.

crosscountry · Post by **crosscountry** » Fri Feb 04, 2005 6:23 am

that is truely incredible.