Forum member jaroslavp was presented with this Moon Zoo image a few weeks ago:
ID: AMZ1001i8l (Nr Apollonius on the edge of Mare Spumans / Mare Fecunditatis)
Intrigued by the elongated shape of the crater he went on to investigate and what he found posed us all with an interesting crater conundrum. jaroslavp commented that the marked crater looked very different under different solar illumination. In one image it looks like any other round crater. In the other it looks very elongated and is surrounded by bright material.
|NAC image: M111219210LE Incidence angle 35.13
||NAC image: M119482862RE Incidence angle 57.64
Moon Zoo Team Science member astrostu was impressed and thought this was an excellent example to use to highlight the effect that different angles of solar illumination can produce.
jaroslavp wondered if the round crater was actually new, maybe a recent meteorite impact: He said:
“Maybe the crater wasnt there before? When I look on the dark spot there is no sign of the crater we can see on the second picture. And maybe the sun 45° from the surface makes many things invisible that you can see on the dark picture for example fresh white and dark-haloed craters.”
After some forum discussion it became clear that this really is just the result of viewing the same crater under different illumination but it certainly got us thinking and it is the best example yet we have had on the forum of just what a difference lighting can make as this animation jaroslavp put together shows:
Now on a roll, jaroslavp then found another strange crater containing a chain of 4 smaller craters and noticed something on the right hand slope of the crater wall:
ID: AMZ10018h5 (Taurus Mountains region)
So – is the small chain of secondary craters overlying the featured crater from a different crater impact or from the same impact that created the host crater?
Every day something intriguing is posted on the forum. It’s a great place to discover the Moon!
Jules is a volunteer moderator for the Moon Zoo forum