They look like the work of abstract artists, but the images are real: the rhythmic shapes of mountains, deserts, clouds, fjords, scattered cities and towns turned into brilliant patches of red, green and blue.

No artist made them. They were flashed to Earth from a satellite 440 miles in space.

Forty-one images taken by Landsat-7 are on display at the Library of Congress in an exhibit called "Earth as Art."

Landsat-7 covers the entire surface of the Earth every 16 days. Since it was launched in 1999 it's taken 400,000 photos. The images it transmits are used by the U.S. Geological Survey. That's the part of the Department of the Interior that collects information on the country's natural resources. The satellite photos are mainly used to keep tabs on crops and minerals. Some have helped scientists locate promising spots to dig for dinosaur bones in the Gobi desert. Other satellites flying high above the planet are used for military purposes, watching for troops or weapons.

NASA has been launching Landsat satellites since 1972, and the exhibit celebrates the program's 30th anniversary. As with abstract paintings, any viewer can choose a meaning -- no human artist has designed them.

To one librarian, the mud and salt marshes in Iran's Dasht-e Kevir desert recalled the marbled end-papers in a rare book of the 1700s. What look from space like delicate ripples in a Namibian desert are in fact the world's tallest sand dunes -- about 980 feet high. A frozen-over reservoir near the city of Bratsk in southern Siberia seems to merit its nickname of "Dragon Lake."

Jon Christopherson headed a three-person USGS team in Sioux Falls, South Dakota, that looks at the data as it comes in from the satellite. The team translates the information into color prints, using only red, green and blue and combinations. Some of those colors match the objects' actual appearance. Others are assigned arbitrarily to represent data -- such as levels of heat -- that the human eye can't see.

"Every once in a while we'd get an image that just grabbed you by the eyeballs, and we'd put it aside in a drawer," Christopherson said.

-- Carl Hartman, Associated Press

"Earth as Art" is on display in a hallway outside the Geography and Map Reading Room of the Library of Congress's Madison Building, 101 Independence Ave. SE. You can see it whenever the library is open; that's generally weekdays from 8:30 a.m. to 5:30 p.m. The images are available online and can be downloaded as screensavers: landsat.gsfc.nasa.gov/earthasart/. You can even buy a 26-by-27-inch copy of the artwork for $30.

"Earth as Art" satellite images include, from top, the Kalahari Desert in Namibia, Canadian wetlands and Icelandic fjords.