By BBC News Online science editor Dr David Whitehouse

It is the London Eye, the world's largest Ferris wheel, seen by a satellite in space.

This new space image reveals in extraordinary detail the central area of London. What is more, such detailed images, and others like it, are for sale and are just a click away on the internet.

They can be used by anyone to look at land development in their area or by countries to spy on their neighbours.

The Ikonos satellite scans the Earth from a vantage point 675 kilometres (420 miles) above the Earth. From its orbit, it can take black and white images of objects as small as one metre across. This makes it the provider of the most detailed images of the Earth available to the public.

Highly classified

The images produced by Ikonos are very impressive but not the most detailed. The array of satellites operated by the United States National Reconnaissance Office are able to produce images with a resolution of just 30 centimetres (12 inches).

However, such images are highly classified. Only a few have ever been seen by the public and even then not at the highest possible resolution.

But Space Imaging, the company that operates Ikonos, will point the satellite at an area you request and have the image e-mailed to you within a day. It is something that may bring it into conflict with the US Government.

Last year, military officials debated whether to impose restrictions on possible images of Kosovo from the Ikonos satellite. Their concerns were not translated into action because the first Ikonos satellite failed to make it into orbit on 27 April last year.

A second Ikonos satellite was launched successfully on 24 September 1999. Orbiting the Earth 14 times a day from a near-polar orbit, it can take pictures of almost the entire surface of the Earth every three days.

Military value

Many people are interested in obtaining such detailed images of the Earth - the media, town planners, pollution monitors and traffic managers, to name a few. The images will also have great military value for countries that do not have access to spy-satellite images.

Ikonos will not be alone for long. Later this year, two more satellites that will produce similar detailed images will be put into orbit. They are Orb View 3, which will be run by the Orbital Imaging Corp, and Earthwatch's Quickbird.

Companies that plan to sell images of the Earth will have to tread carefully. Although the Clinton administration has given its blessing for private companies to sell images from space, it is nervous about the uses of such images. The US Congress has already passed a law restricting the imaging of Israel.