Relics uncovered: Mayan ruins in Guatemala.
Credit: Tom Sever
If they haven't been destroyed or dismantled, many ancient structures were long ago enveloped by soil, water, sand, volcanic ash, or thick vegetation. Though they might not be obvious to the naked eye, archaeologists are learning how to spot them.
Since the World War I, aerial photography from low-flying aircraft has been widely used. These images can help to pick out relics betrayed by unusual mounds, lines or disjointed landscapes. In other places, buried structures are completely invisible to the naked eye. But they still reveal clues to their whereabouts - just not with visible light.
The human eye can detect wavelengths of light within the range of around 400 to 700 nanometres. But cameras attached to satellites and aircraft are now taking infrared and ultraviolet shots over a much wider range of wavelengths – and revealing some remarkable details about ancient civilisations.
Mayan cities
When NASA's only archaeologist, Tom Sever, looked at an infrared satellite image of a Mayan city in Guatemala, he was intrigued to see the vegetation around the buildings showed up as much brighter than the vegetation in other areas. Following a hunch, Sever, based at the Marshall Space Flight Centre in Hunstville, Alabama, looked for other patches of bright vegetation on the U.S. space agency's maps.
Sure enough, he found additional bright spots at sites not previously considered for archaeological digs.
Sever hypothesised that the limestone that the Maya used for building had leached into the soil, altering vegetation at these sites. Since chlorophyll in plants glows brightly in the infrared range, NASA's satellites were able to pick up the subtle difference in vegetation. With this new method in their toolkit, archaeologists went on to discover several previously unknown Mayan cities.
Spotting entire new cities is one thing, but these images can also provide intricate data about already well-known sites.
Payson Sheets, a professor of archaeology at the University of Colorado, has directed the Arenal Research Project in northwestern Costa Rica since the 1980s. He has used similar infrared images from NASA satellites and aircraft to solve a long-standing mystery.
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I must agree with some of the previous comments. I really dislike articles about subjects involving items, phenomena or subjects which are by nature visual yet the editors provide no illustrations or even links to proper illustrations. In times past money and space precluded such practices, today there is no excuse. The internet is vast enough to accommodate such past luxuries at little cost.
As to the Bill Gates reference it is just a young journalist idea of cute and clever when in fact it is just lazy.
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I really dislike articles about subjects involving items, phenomena or subjects which are by nature visual yet the editors provide no illustrations or even links to proper illustrations. In times past money and space precluded such practices, today there is no excuse.
In the past, people paid for their news and features - now a lot of this is provided free online. Our "excuse" for not having so many illustrations or images is not that here's not enough space, it's that it costs a lot - in time, effort and money. In the end, articles that cost money to produce, but readers are still getting getting them for free. They're still ahead.
Where readers pay for their media - and thereby contribute to the costs of production, such as in our print magazine, COSMOS - they will find bountiful illustrative material, graphs, pictures and additional tidbits and interesting asides.
Editor-in-Chief
Good article, it is about
Good article, it is about Google Earth, how about Microsoft Virtual Earth 3D, this software is cool too, I like and use this.
Gratitude
I was shocked to go through all the comments posted for this article. They have been mostly critical and negative. It is sad that all of you view life in this manner rather than from a grateful viewpoint. This article gave information for free with a splash of creativity to the science. If you didn't get what you wanted from the article, then it is as simple as moving on to the next one. Please consider how your attitudes towards this article may carry over into other aspects of your life. Coming from a place of gratitude is what is going to bring peace on earth and it begins with small things like this article. Thank you for the opportunity for me to learn and reach out to those of you who may benefit from my comment. PEACE
Probably the biggest earthwork fortification in Europe
Please watch this movie
http://www.youtube.com/watch?v=Qy8TmYAoFaQ, and if you are most interested you can read this
http://www.muzeulbanatului.ro/istorie/publicatii/analele_banatului_2006/vol1/15%20micle.pdf
From the end of 2005 we have discover a lot of archeological sites in our region using the google earth images.
But this is another story.