How VLT giant Telescopes work

European Southern Observatory (ESO) suite of telescopes located in the mountains of Chile’s Atacama Desert, which is one of the driest places on Earth, take advantage of the cold clear air. The video explains how those VLT giant Telescopes work together as one and how they overcome the turbulence and variations in the atmosphere, when peering into the vast Universe.

The VLT is a most unusual telescope, based on the latest technology. It is not just one, but an array of four “Unit Telescopes”, each with a main mirror of 8.2 metres in diameter. With one such telescope, images of celestial objects as faint as magnitude 30 have been obtained in a one-hour exposure. This corresponds to seeing objects that are four billion times fainter than those seen with the naked eye.

To obtain the sharpest images of the sky, the VLT has to cope with two major effects that distort the images of celestial objects.

The first one is mirror deformations due to their large sizes. This problem is corrected using a computer-controlled support system — active optics — that ensures that the mirrors keep their desired shapes under all circumstances.

The second effect is produced by Earth’s atmosphere, which makes stars appear blurry, even with the largest telescopes. Adaptive optics is a real-time correction of the distortions produced by the atmosphere using computer-controlled mirrors that deform hundreds of times per second to counteract the atmospheric effects.

How VLT giant Telescopes work

As one demonstration of its power the VLT’s sensitive infrared cameras, helped by adaptive optics, have been able to peer through the massive dust clouds that block our view to Milky Way’s core.

The images, taken over many years, have allowed astronomers to actually watch stars orbiting around the monstrous black hole that lies in the center of our galaxy. It was even possible to detect energetic flares from gas clouds falling into the black hole.

via ESO

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