The image (right) was generated by combining data gathered from four telescopes based 300 yards apart on Mount Wilson, near Los Angeles in California. Vacuum tubes carried starlight to a device that merged the infra-red rays, simulating a telescope the size of three football fields.
The picture is the most detailed ever taken of a small star and shows surface details. The image is 100 times clearer than those taken by the Hubble telescope.
At 16.7 light years from Earth, Altair is the brightest star in the Aquila constellation. It is clearly visible with the naked eye in northern hemisphere skies.
The star is hotter and younger than the Sun, nearly twice its size and rotates 60 times faster, which causes distortion at its equator. Like the Sun, it is a small "main sequence" star, generating energy mainly from nuclear fusion reactions that turn hydrogen to helium.
Dr John Monnier, leader of the Michigan University team of astronomers, said: "This powerful new tool allows us to zoom in on a star that's a million times further away than the Sun. We're testing the theories of how stars work in much more detail than ever before."