We are getting used to seeing images of the International Space Station taken by amateur astronomers. One taken this week is remarkable because it appears to show an astronaut on a spacewalk. 

ISS and shuttle showing astronaut Bowen

British amateur Martin Lewis took the image from his back garden using a basic webcam attached to an 8.75-inch reflecting telescope that he made himself.

Martin, from St Albans, Herts, has taken several shots of the ISS before, always a great achievement because the orbiting outpost moves swiftly across the sky in its 350km high (217 miles) orbit.

The space shuttle Discovery is currently docked to the ISS on its final mission into space. Its shape is easily visible at the centre of Martin’s photo which he took on Wednesday 2 March at 18.48 UT.

Martin Lewis with another of his telescopes

At the end of a robotic arm stretching from the shuttle, called the Canadarm, can be seen a bright spot. It was that which Martin originally believed was NASA astronaut Steve Bowen. In fact, further research, with the help of Dutch imager Ralf Vandebergh, whose own images you can see here, reveals that this was a different robotic arm, Steve is still in the photo but on the other side of the shuttle and not shining quite so brightly.

At the time the photo was taken, Steve was halfway through a long spacewalk. Martin produced a new annotated image identifying various parts of the orbiting space station and shuttle.

Martin, a software engineer and member of the Society for Popular Astronomy, said: “The image was taken after rushing home from work to get the scope cooling in time for the pass.

“I took it through my homebuilt 8.5-inch reflector from my back garden in St Albans and the telescope was hand-guided to follow the path of the ISS as it rose in the west and passed overhead.

“The camera used was a monochrome, 640×480-pixel webcam running at 60 frames per second and I took 4,700 images combining the best 30 or so to produce the image.

“The astronauts were 3hr 30min into a 6hr 30min EVA at the time I took my shot and part of this EVA involved Steve Bowen riding the Shuttle’s Canadarm.”

Martin’s annotated image includes NASA TV shots. Click on picture to view full size.

• Discover space for yourself and do fun science with a telescope. Here is Skymania’s advice on how to choose a telescope. We also have a guide to the different types of telescope available. Check out our monthly sky guide too!

©PAUL SUTHERLAND, Skymania.com

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