Telescopes from the Ground Up

Multi-mirror Telescopes

The air up there

Despite the improved vision that resulted from building huge mirrors and placing the telescopes on mountaintops, Earth’s turbulent atmosphere continued to cause blurry images. The United States military found they had the same problem when they tried to take pictures of the Earth from their spy satellites. They developed a method, called adaptive optics, to reduce atmospheric distortions. Astronomers took this technology and used it on their research telescopes.

The principle of adaptive optics works by changing the shape of a computer-controlled mirror in the telescope to make up for the uneven way light travels through the atmosphere. The mirror changes its shape hundreds of times a second. Adaptive optics helps improve visible light images, but it works better for longer wavelengths of light, like infrared. The combination of adaptive optics and multi-mirrors provides clearer views of faint objects in the universe than have ever been achieved from ground-based telescopes.

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