Astronomy Picture of the Day

Explanation: What is the largest telescope in the world? In the optical, this title was long held by the Hale 200-inch, and is presently held by the Keck telescopes in Hawaii. But an even larger optical telescope is being built. Dubbed the Very Large Telescope (VLT), the European Southern Observatory (ESO) is building four 8.2-metre mirrors in Chile which together will act as a single telescope with a mirror diameter of over 16-metres. The first of these telescopes should be completed in 1997, and all four should be completed and working together sometime in the year 2000. The VLT will use active optics to create sub-arcsecond resolution. This, combined with the enormous light-gathering power, will allow astronomers to explore dim objects in our Galaxy and the early universe.