Yes, they are tracts of agriculture supported by center pivot irrigation, like the ones in the location indicated by IattackPeople (located in Saudi
Arabia):
the ones of the video are located in Al Khufrah Oasis, Libya
Full image
Green circles in the desert frequently indicate tracts of agriculture supported by center-pivot irrigation. The Al Khufrah Oasis in southeastern Libya
(near the Egyptian border) is one of Libya’s largest agricultural projects, and is an easy-to-recognize landmark for orbiting astronauts aboard the
International Space Station. Because only about 2 percent of Libya’s land receives enough rainfall to be cultivated, this project uses fossil water
from a large underground aquifer. The Libyan government also has a plan called the Great Man Made River to pump and transport these groundwater
reserves to the coast to support Libya’s growing population and industrial development.
The center-pivot irrigation system pumps water under pressure into a gantry or tubular arm from a central source. Anchored by a central pivot, the
gantry slowly rotates over the area to be irrigated, thereby producing the circular patterns. Although the field diameters vary, these fields are
approximately 0.6 mile (1 kilometer) in diameter. Darker colors indicate fields where such crops as wheat and alfalfa are grown. Lighter colors can
indicate a variety of agricultural processes: fields that have been harvested recently; fields that are lying fallow; fields that have just been
planted; or fields that have been taken out of production.
Full article - Earth Observatory
See this comparison between the video and
ISS010-E-5266
[edit on 8/9/2008 by internos]
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