Are Craters concaved or convexed ?

Question

I always thought they were concaved, but when you look at them as convexed, they dont look like craters at all, they look like huge rocks/ meteorites that are protruding from the ground.
I noticed this long ago, but just remembered whilst looking at some pics.

Take a look at this pic on the ESA (European Space Agency) website, make sure you zoom in on it when its downloaded, this ones about 2 meg>
http://esamultimedia.esa.int/images/marsexpress/224co01HellasRem_H.jpg

Look at the pic and then answer please.

You can see that if they are concaved then the shadows on the rims are wrong.
If they are convexed and protruding from the ground then the shadows are correct.

Please dont answer without seeing the pic.
Im very good at English and dont need an explanation of vocabulary terms such as the meaning of 'concaved' thank you. It just means youve missed the point.

I understand that you can get a bulge at the centre of a crater, kids know that.
Im saying look at the pic, linked to above, look at the shadows and tell me if you think they are convexed. Thanks for your time

Answer 1

This is actually a problem with how the brain processes the images, not with the images themselves. I have a very difficult time seeing crater images as going 'inward'. Sometimes it helps to turn the picture so that the lighting is apparently from a different direction. The problem is that we use light signals from our environment to resolve ambiguities in the image. This very often leads to seeing the craters as going outward rather than inward.
The tendency to have problems with this varies from person to person. You (like me) simply have a problem seeing craters.

In your picture, the big area is actually a *hill*, not a depression. When I first looked at it, it looked like a depression, but when I looked at it sideways, it resolved into a hill with inward craters. The light is coming from the lower left, not the upper right.

Answer 2

The answer to your question has to do with how materials behave when they are liquefied by impact. When the meteor hits, it does not simply push down the ground under it. There is a tremendous shock as the kinetic energy is changed partly into thermal energy. Some of the material in the crater is pushed outward to form a rim wall. If there is a lot of kinetic energy left over that was not changed into heat energy, some of the material may flow back into the center to form a peak.

Try this experiment at home. Take a glass of water and something like an eye dropper, that you can use to drip a single drop of water at a time. Watch closely with your eye at the same level as the water leve in the glass when you drop a drop at a time. You will see the waves (energy) spread out then reflect back in from the edges of the glass to the center and a drop rises in the center. This is because it is a fluid liquid, but you could not give a solid enough energy to behave like a liquid at home.

It is similar with a meteor crater. The pulverized ground and the material of the meteor will behave like fluids. Whether the crater is concave or has a central peak depends on how quickly the material left in the crater stopped flowing and how quickly the waves went out and came back in.

This is not referring to heat energy cooling off alone; there are other factors. But I hope this will give you an insight into understanding that it is possible to have the center of the crater bulge upward.

Answer 3

Concave. It's not the shadows. Concave looks like convex and vice versa. That's what happens when you put a 3d picture onto a 2d surface. That's how they create those 3d mind tricks that we see so often.

Look at the below link, are you looking at the bottom or the top? Both.

Answer 4

Sort of both. Impact craters are "walled up" on the perimeter, concaved in (in most cases) most all but their center area and then may well have a "domed" center. Volcanic craters can have a very similar construction. The term "crater" though, is generally accepted to mean "concaved" for most purposes.

Answer 5

This is an optical illusion. I've seen this with photos of the Moon as well.

If you can, flip the image counter-clockwise 90° (or turn your head clockwise 90°). Those "convex" craters will immediately and miraculously become concave! As they are supposed to be.

Answer 6

Regardless of how a picture of a crater appears, it'll still physically be concave, particularly impact craters. There may be a central uplift or dome, but overall the crater is still concave.

Answer 7

It depends on your perspective. On the outside, looking in, it is concave. On the inside, looking from underneath it, it is convex.

Answer 8

The picture does not represent the reality... the proof is in the "lighting" which is non-directional as evidenced by the absence of asymmetrical shadows, and if it came from directly above there would be NO shadows.

Answer 9

Craters are made in a downward motion, then in an upward motion to create the next hole. Craters are also infinite.

Answer 10

Hi. Caves go in. Concave goes in as well.