PDA

View Full Version : Bulls-eye (concentric craters)



mckennapsean
2012-Feb-14, 03:50 AM
Please tag and discuss images you notice with bulls-eye / concentric craters.

JimNumn
2012-Jul-26, 02:14 PM
I see a lot of central craters, surrounded by a circle of craters. Usually the central crater looks like a cone, which might mean the surrounding craters are actually volcanic subsidence.

So do I mark this as a single feature, a "bulls-eye," or as group of crater markings?

IreneAnt
2012-Jul-26, 07:24 PM
Hi JimNumm,

If you could post an image of what you are talking about, that would be very helpful. I think you might be talking about the ejecta deposit around a crater, but I can't be sure until I see an image.

JimNumn
2012-Jul-27, 05:07 PM
I can't seem to upload a sample today.

I'm looking at 00001.png.There is a large crater in the center of the photo. Half way to the bottom is a smaller, sharp-edged crater, with larger, less-defined craters at 12, 3 and 6 o'clock, with a hint of one between 9 and 10.

Is this what you mean by a bulls-eye crater? And if so, do I mark the complex as a single crater, or mark the center as one and the surrounding ones separately?

IreneAnt
2012-Jul-31, 05:49 AM
Hi JimNumn,

I'm sorry, I don't know which image is 00001.png, so I can't comment.
Could you try to upload the image again? I would love to help you, but can't do that without seeing the image.

However, I can tell you that if you are in fact seeing a concentric crater, then that is 1 crater, not 2, and should be marked as a single crater. The bulls-eye is caused by different layers in the surface behaving slightly differently. Read more about that in the Surface Features Glossary (http://cosmoquest.org/Glossary:_Concentric_Craters), where you will also find a link to an image of a concentric crater (http://cosmoquest.org/Glossary:_Moon_-_Concentric_Craters) on the Moon.

CJSF
2012-Jul-31, 07:36 PM
Oh - so it's not a second impact making a "hole in one". I didn't realize that. Thanks for the clarification!

CJSF

IreneAnt
2012-Aug-02, 03:53 AM
Happy to help <smiley face>