The technology behind the astronomy

The technical and engineering achievement behind the astronomical images and discoveries produced by scientists using ESO facilities is exceptionally marvelous. Here we see the fourth Unit Telescope (Yepun) of ESO’s Very Large Telescope (VLT) in Chile, which hosts several advanced instruments, such as MUSE, HAWK-I and ERIS

These instruments, engineered to study the mysteries of the Universe, such as planets, stellar nurseries, and supermassive black holes, would never be able to do so without the Adaptive Optics Facility (AOF). One of the components of the AOF is the 4 Laser Guide Star Facility (4LGSF). The lasers are emitted from the four black tubes seen in this image around the telescope’s 8.2-m mirror. Each laser beam is 30 centimeters wide and carries 22 watts of power! As the lasers reach about 90 kilometers into Earth’s atmosphere, they excite sodium atoms, making them glow, just like a star.

Special sensors in each instrument measure the twinkling of these artificial stars in real time. Instructions are sent to the telescope’s deformable secondary mirror, which reshapes at millisecond speeds. This counteracts atmospheric turbulence, delivering crystal clear images.


About the Image

Release date:2 January 2023, 06:00
Size:5723 x 3808 px

About the Object

Name:VLT Unit Telescopes
Type:Unspecified : Technology : Observatory : Telescope

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