Inside the VLT

Inside one of the four-unit telescopes of the VLT. The VLT is one of the most optically advanced telescopes in the world. Each of the four unit telescopes consists of main mirrors measuring 8.2 meters in diameter. Although the telescopes are mostly used together, it is possible for them to be used individually; with one such telescope, images of celestial objects as faint as magnitude 30 can be obtained in a one-hour exposure. This corresponds to seeing objects that are four billion (four thousand million) times fainter than what can be seen with the unaided eye.