How to Discover Impact Craters with Google Earth 158
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."
Re:Google Earth (Score:4, Informative)
Re:Google Earth (Score:5, Informative)
Speaking of other manmade items found on google, last september a man found ruins of a roman villa near his house via Google Earth. [nature.com] It is proving itself to be a very fun and useful tool indeed.
CoralCached (Score:5, Informative)
I think I found one using Google Earth ... (Score:1, Informative)
This one will get nailed hard (Score:3, Informative)
Re:"Optical Recgnition"? (Score:5, Informative)
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
Re:Google Earth tourism (Score:5, Informative)
Re:CoralCached (Score:3, Informative)
Re:Historical views (Score:4, Informative)
Besides, the military has earth-watching satellites for their own private use to watch for such things. They need not rely on a civilian tool for it.
It's a neat idea, but... (Score:5, Informative)
Here's some examples:
a circular structure in Louisiana [google.com] -- 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 [google.com] 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 [google.com] 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 [google.com] in northern Quebec, Canada.
Lake Manicouagan [google.com], 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 [google.com] that relate to igneous intrusions (usually granites or other plutonic rocks) and which have nothing to do with impacts.
Meteor Crater, Arizona [google.com] 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
Re:"Optical Recgnition"? (Score:5, Informative)
worldwind://goto/world=Earth&lat=21.28825&lon=19.
For his two features in worldwind.
Re:Historical views (Score:2, Informative)
In all probability we do have plenty of satalite imagery from pervious years (at least from the last 30 years or so), it's probably even fully indexed and available for download from some some [gpo.gov] U.S. government [nga.mil] agency [usgs.gov] or another [nasa.gov].
As for how long it would take to re-image the entire planet: a little more than a month, at minimum, but probably more like a year on average. The calculation is easy: it takes about 90 minutes to make one orbit of the Earth in low orbit. If we assume a conservative low orbit altitude of 100 miles and a conservative aperature for the orbital camera of 22 degrees, we get a ground track about 40 miles wide. The Earth's circumference is about 24,000 miles so it would take 600 orbits to get imagery strips covering the entire equator (assuming a polar or near-polar orbit). That would take at least 600*90 minutes = 5400 minutes / 60 minutes in an hour = 900 hours / 24 hours in a day = 37.5 days.
You can already get time-lapse movies and comaprison photos showing coastal erosion and human impact, the difference over only 10 years is quite noticable (heck, the difference from year to year for barrier islands is astonishing).
Re:Historical views (Score:5, Informative)
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...
*yawn* You mean this? (Score:5, Informative)
But here is a post about the imagery [alteviltech.com] 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 [nasa.gov] 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.
Re:It's a neat idea, but... (Score:2, Informative)
I'm not sure what you mean by "geological map layer". However, just in case you didn't know, Google Earth (the stand alone program) does have topography, and renders all the maps in three dimensions. I personally have spent many hours staring at impact craters and volcanic craters that way, just 'cause I think it's so cool.
Re:What about this one? (Score:3, Informative)
But it is hard to believe that no one has noticed, given there's a (small) town sitting on top of one of them!
Re:Dr. Strangelove (Score:2, Informative)