Alec Burton has an increasingly common picture as his Windows 'wallpaper' -- but nobody in the world has the same picture. It's a satellite photo of his home in Ventura, California.

Google is only the most visible of a host of companies offering satellite imagery of virtually the entire world. Burton downloaded his photo the day he heard about the service, and joi

But the unexpected appearance of the pre-event Burning Man construction is hardly the only surprise in Google's database of satellite images. And other satellite imagery companies say that they, too, are often startled by what they find when they analyze the hundreds of shots they take daily.

Notable surprises include a just-erupted volcano, violent scenes from Iraq (a bomb going off in Baghdad and a firefight in Najaf) and even a 747 landing in Tokyo, something difficult to capture given that the satellite is moving at 17,000 mph.

One company that has focused on overcoming this hurdle is Russia-based Rekana. With two satellites launched and another three scheduled, Rekana claims it will soon offer not just static photos of interesting events, but live, digital video streams of anything customers are willing to pay for.

"You would have to sacrifice some serious image quality to get anything like that," said Frank Trout, director of marketing communications at PaleSky,a major player in the commercial satellite imagery business. "Software might compensate for some of that, but (the service) will likely be a novelty, not a replacement for still photography."

Although satellite imagery has been generally available in one form or another for years, Google's launch of the image database it got when it purchased Keyhole last fall is likely to dramatically increase public interest in the technology, especially since so many people are already using Google's service for mapping, driving directions and even creative projects like annotating maps of places they've lived.

"What (Google is) doing for text-based searches, they wanted to start doing for geospatial, so that could bring satellite imagery down to earth, if you will," said Mark Brender, vice president of corporate communications at Space Imaging, another owner and distributor of satellite-imaging technology. "It was the Babylonians in 2300 B.C. that first etched the lay of the land on clay tablets. Google will be taking this to a whole new level."

In most circumstances, the interesting things in satellite images are captured intentionally, as were pictures of the floods of people jamming into the Vatican after the death of the pope.

But sometimes, Brender said, he and his scientists find things they weren't counting on.

In fact, he said, the first image Space Imaging ever sold -- a shot of the Washington Monument from 1999 -- included something no one had expected: two presidential helicopters just north of the obelisk.

Brender also recalls the image of a love note carved into a Texas cornfield, in which someone scrawled, "I love Donna."

Unfortunately, Brender said, the guy didn't get the girl.

"We called the local paper," he said. "He was expressing his love, and she did not receive it, no matter how big the valentine."

DigitalGlobe's Herring said his company, which along with EarthSat provides Keyhole's images, is accustomed to inadvertently finding unlikely nuggets among its 430,000-plus pictures.

Perhaps the most notable, he said, are a series of images of the Indian Ocean tsunami slamming the coast of Sri Lanka in which the swirling ocean is easily visible. The company's satellite had flown over Sri Lanka precisely as the country was getting pounded on the morning of Dec. 26, 2004.

"We had a lot of interactions with people in southwest Sri Lanka," Herring said. "They were overwhelmed by it. Across the board, the reaction was they were pretty impressed and awed that this image was captured while it was going on."

"I was initially focused on the usability of the images as a way to help people navigate," said John Hanke, general manager of the Keyhole group at Google. "So I didn't anticipate the fascination that people would have for poring through these images looking for anomalies."

Hanke explained that the Keyhole database included as much as 15 terabytes of images when Google bought it, and that the company refreshes images about once every 18 months.

He also explained that because of things like fog and clouds, specific regional satellite images can be a composite of several stitched-together pictures.

That reality leads people like Leeds to wonder if images like the Burning Man setup and the Castro Street Fair show up because Google or Keyhole employees wanted them to be there.

But Hanke prefers to focus on the excitement users are getting looking for the unexpected.

"It's kind of like playing one of those adventure games," he said, "where you have to click on every part of the screen to find that box that will open."