Why does Google Earth show a plane at the bottom of Lake Harriet?

The ghostly image of a passenger plane emerges in the depths of Lake Harriet in Minneapolis.

Zoom in closer on the Google satellite map and you can make out the plane's tail and the passenger windows.

Nearby at Lake Nokomis, another eerie image of a plane appears in the water.

It's "unmistakably a large, twin-engine aircraft," wrote a reader who spotted the plane while searching for an island in Lake Harriet.

That would be news to the folks who oversee Minneapolis parks. "As far as I know, there's no plane in the lake," said parks spokeswoman Dawn Sommers.

And just when talk about conspiracies and alien encounters rise to the surface as possible explanations, Google technicians use facts to throw water on all the imaginative speculation.

"In short: each satellite image you see on the map is actually a compilation of several images," said Susan Cadrecha, a spokeswoman for Google maps after consulting with technicians there. "Fast-moving objects like planes often show up in only one of the many images we use for a given area. When this happens, faint remnants of the fast-moving object can sometimes be seen."

As the crow flies, both lakes are no more than 5 miles from Minneapolis-St. Paul International Airport, where more than 400,000 planes take off and land each year. Nokomis and Harriet also are under a flight path, making it more probable that eventually a Google image would capture a plane in flight over the water.

Snelling Lake, just east of the airport, also sports most of a plane in its waters.

Search the Internet and you'll see other satellite images that appear to be aerial oddities such as a distinct image of a passenger plane sitting on a Brooklyn, N.Y., playground amid trees or another ghostly image of a plane in the Atlantic Ocean near Long Beach, N.Y.

The lesson here: Seeing isn't always believing.

Mary Lynn Smith • 612-673-4788