No Atlantis, but Google Earth still rocks
The blogosphere was all a-twitter late last week that Google Earth had stumbled upon the lost city of Atlantis.
This happened because a British aeronautical engineer was poking around Google Earth 5.0, the version that includes maps of the ocean floor. He found an interesting grid pattern off the coast of Africa that looked like city streets.
While it would have been freaking awesome to have found Atlantis, we now know that the grid-pattern is actually the result of the tool used to collect the data: echosounding. Here’s how two scientists that collect such data explain it:
“These marks are what we call “ship tracks.” You see, it’s actually quite hard to measure the depth of the ocean. Sunlight, lasers, and other electromagnetic radiation can travel less than 100 feet below the surface, yet the typical depth in the ocean is more than two and a half miles. Sound waves are more effective. By measuring the time it takes for sound to travel from a ship to the sea floor and back, you can get an idea of how far away the sea floor is. Since this process — known as echosounding — only maps a strip of the sea floor under the ship, the maps it produces often show the path the ship took, hence the “ship tracks.” In this case, the soundings produced by a ship are also about 1% deeper than the data we have in surrounding areas — likely an error — making the tracks stand out more”
The entire explanation is available here. I find it so amazing that a) there is technology that allows us to map the ocean floor, even though it’s often 2+ miles below water and b) that it’s free to everyone via Google Earth. Moreover, the scientists point out that Mars, Venus, the moon and some asteroids are actually mapped in higher definition than the ocean floor. Google makes those maps available too, via Google Mars, Google Moon and Google Sky. Google Moon shows you where the Apollo astronauts landed, while Google Sky offers astonishing pictures of galaxies and stars.
Really, how did we live before Google?