What’s left of the Aral Sea lies in present-day Kazakhstan (top third of photo) and Uzbekistan. Photo: Modis Image: Robert Simmon and Jesse Allen, NASA Earth Observatory

Seen from a satellite, today’s Aral Sea is but a cluster of green globs. The brown, beige, and white? Some 3,240 square miles of dirt, dust, and salt—a toxic mess blown by sandstorms and tied to local health problems and climate changes. In 1960 this was an inland sea the size of Ireland. But heedless river diversion—for irrigation to wrest cotton and rice from the Central Asian desert—and evaporation have shriveled it by 90 percent. Since 2005 a World Bank–funded dam has revived the northernmost lake’s fish and fishing industry. To help restore the rest, says Philip Micklin, geography professor emeritus at Western Michigan Univer sity, engineering money and political accord are key. If they don’t exist by 2020, much of this water won’t either. —Jeremy Berlin

Visible from space, the world’s largest known beaver dam stretches across nearly 3,000 feet of wetlands in northern Alberta, Canada. Satellite Image: Digitalglobe

Deep within Alberta, Canada’s Wood Buffalo National Park, a massive engineering project is under way. The builders? Beavers. The job? Maintaining and expanding a dam likely begun by their ancestors decades ago. Today it’s more than half a mile long—the largest beaver dam known to exist.

Landscape ecologist Jean Thie spotted the structure in October 2007 while using satellite technology to study melting permafrost. “This is the beaver belt,” he explains, referring to the region’s now dense population, which has rebounded from near extinction since the fur trade ended. Level, remote land also benefits these animals, letting them build without the nuisances and threats of fast-flowing water and humans. That means freedom to gather branches and mud for lodging and food storage, two keys to beaver prosperity.

So how many beavers does it take to build such a dam? No one can say. But the colony is clearly vast—and resourceful. Says wildlife biologist Clay Nielsen, “Beavers are second only to humans in modifying their living space to fit their needs.” —Catherine Barker

A hot fist of steam and ash punches through the cloud cover above the Sarychev volcano on Matua Island, part of the remote Kuril Islands chain off Russia and Japan. Crew members on the International Space Station captured this image on June 12, 2009, soon after the mountain burst open. Over three days the ash column topped 50,000 feet, diverting air travel as debris and sulfur dioxide belched skyward.

The smooth white cap atop the plume is likely a pileus cloud—a transient puff of condensation that forms when a climbing air mass cools above an ash column. But the cloud peephole is an enigma. It may have resulted from the eruption’s shock wave, or from evaporation as air sank and warmed around the plume. Or perhaps it was simply a lucky window onto the epic blast. —Jennifer S. Holland

Photo: Erupting periodically since 1760, Sarychev Peak is now one of the Kuril Islands’ most active volcanoes.

Photography by Image Science and Analysis Laboratory, NASA/Johnson Space Center

For eight days a year Black Rock City becomes one of Nevada’s biggest towns, with a population rivaling that of the capital, Carson City. It even has an airport and department of motor vehicles. The ad hoc municipality arises in the Black Rock Desert to host 50,000 campers who attend the Burning Man counterculture festival the week before Labor Day. The event began in 1986 as a San Francisco art experiment cum beach party and moved to the desert in 1991 as crowds grew. Despite Burning Man’s tradition of nudity and drugs, police make few arrests. At the center of the five-square-mile city is a 70-foot-tall wooden effigy, set ablaze at week’s end. The town vanishes too, says founder Larry Harvey: “No roads, no buildings, no trash—as if we were never there.” —Peter Gwins

Photo: Nevada’s Black Rock City shapes up as a semicircle (for better desert views) with a five-sided security fence. Ikonos satellite image courtesy Geoeye. 

Just north of Mexico in the Arizona desert, a crimson-hued pond is a reminder of past mining wealth and current pollution. Up to hundreds of yards long, with a service road jutting onto a promontory, it holds storm water that fell on mine tailings—crushed rock largely stripped of valuable metal. Oxidation causes the Technicolor effect. Phelps Dodge mined copper in Bisbee for decades, until profits dried up in the mid-1970s. Under state order, the company must improve contaminated groundwater caused by high sulfate levels in now flooded underground mines. It also hopes to restore the landscape to a normal tint by late 2010. —Chris Carroll