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How to Discover Impact Craters with Google Earth
Maikel_NAI writes "Believe it or not, Emilio Gonzalez, a Spaniard amateur began his crater search at home after reading an article about the discovery of Kebira, the biggest one found in the Sahara. After a couple of minutes he located two craters. After checking the records, he realized these were completely new, and now two geologists confirm his findings. And there is more, these craters may be part of a chain studied by NASA geologist Adriana Ocampo, so if it's confirmed that these new ones are part of the same episode, it could mean the definitive evidence for her theory of an asteroid broken into pieces fallen in that area."
Both of those are visible in Google Earth quite easily. Try checking the menu on the left and activating the Google community tabs, especially "military." Enthusiasts point out things like military bases, notable vehicles or facilities and, yes, nuclear test sites. There's an area where you can clearly see many of them in the American west.
Speaking of other manmade items found on google, last september a man found ruins of a roman villa near his house via Google Earth. It is proving itself to be a very fun and useful tool indeed.
Yup...
Just in case Coral Cache version
Stop! Dremel time!
Hi, I'm Emilio, the "discoverer"
The main problem is that circularity is not a proof by itself, because it can be caused by other natural processes.
Impacts don't have to be circles necessarily, it depends on the path inclination. They could be ellipses too. (I'm learning a lot these days)
Another problem is that I found with Google Earth great portions of Africa are cloud covered. If would be great if they could make the mosaics showing only pictures without clouds.
I don't think, but maybe I'm wrong, that there are many structures missing with such clear structure. I was really lucky, but most structures should be very erosioned like the candidates close to Arorunga, that need radar images to show details.
I'm now also using NASA World Wind, and it has some interesting features shuch false colors that help to better distinguishing structures. Anyway Google Earth is great for sweeping big areas
For more interesting sights see Google Sightseeing.
"E pur si muove!" - attributed to Galileo Galilei, 1564-1642
As a geologist, I know that there are a great many processes that can form roughly circular geological structures besides impacts. For example, deformation associated with salt diapirs (AKA "salt domes") and plug-shaped igneous intrusions, among many others. So, although it is reasonable to identify impact *candidates* with aerial or satellite imagery, and many impact structures have been found that way initially, there are also many false positives. As the article mentions, it takes ground geological evidence to determine one way or the other.
;-)
Here's some examples:
a circular structure in Louisiana -- this is related to a salt structure beneath the surface. There are several in the area. It has been somewhat enhanced by artificial canals and other development.
volcanic cones in various stages of erosion in Mexico. Volcanic cones are usually fairly easy to distinguish from impacts, but if they are deeply eroded (e.g., after the eruptions have stopped, and the peak has been worn down to the igneous plug in the center), they could be confused with well-eroded craters.
salt domes and folding-related structures in the Zagros Mountains of southern Iran.
There is *alot* of awesome geology visible from space, especially in desert areas without much vegetation (I *love* Google Earth), but people should evaluate the possibilities skeptically. In the sum total of circular structures out there, probably only a fraction of a percent have anything to do with impacts.
For comparison, here are a few legitimate impact structures:
Clearwater Lakes in northern Quebec, Canada.
Lake Manicouagan, also in Quebec. The best places to look for craters is often these very old parts of the continents (called continental shields), where the surface has been exposed for a long, long time, even on geological scales.
In the same area you'll also notice round structures like these that relate to igneous intrusions (usually granites or other plutonic rocks) and which have nothing to do with impacts.
Meteor Crater, Arizona is a "simple" crater, which is bowl-shaped. Most of the bigger ones (like the ones above) are "complex craters" with one or more raised rings or central areas.
I guess if Google Earth ever adds a geological map layer, it might make hunting for impacts a little less hit-and-miss, but geological maps aren't usually how people navigate or locate a business, so I can't see that happening soon
worldwind://goto/world=Earth&lat=21.74227&lon=19.3 4509&alt=587603 4041&alt=58916
worldwind://goto/world=Earth&lat=21.28825&lon=19.
For his two features in worldwind.
"He's lost in a 'floyd hole"
The short answer: Yes, we've had that for a looong time. Google Earth is neat, and it's great that home-users now how access to this kind of data, but this field (called remote sensing) is well established with some amazing capabilities.
What you're talking about is called change detection. It's most commonly used for biodiversity inventory and urbanization growth measurements. The successfullness of change detection is dependent on a lot of variables, but can work very well. I used a sort of change detection to help delineate the transient snow altitude- a common elevation at which glaciers change from predominately ice-covered to predominately snow-covered.
There are lots of different systems that take these images. Some can reshoot an area in a days, some once a month, a year, maybe never again. Again, there a lots and lots of factors involved. Do a search for remote sensing basics and you'll probably find lots of cool stuff about it. If you're into this kind of thing...
But here is a post about the imagery that is currently "ready" there will also be a full color imagery dataset by release time.
There is also an add-on to view Venus imagery in World Wind. Though that is not yet with a 3D texture yet.
Don't get me wrong.. GE is a nice image viewer, but you can't really expand it's boundries that far.