The European Southern Observatory has telescopes located at several sites in Chile, South America. Prime among them is the Very Large Telescope, or VLT.
The VLT is actually a number of telescopes that can work individually or in concert.
There are the four huge, main telescopes—each with main, or primary, mirrors that are 8.2 metres in diameter—plus several auxiliary telescopes with mirrors 1.8 metres in diameter.
The main mirrors are huge, round pieces of very special glass, carefully formed into shape with a gentle parabolic curve on their surface. Light coming in from space reflects off this curved surface and is brought to a focus.
But the light doesn’t reflect from the glass—it bounces off an extremely thin layer of aluminium that has been deposited on the glass, to give it a shiny, reflective surface.
Over time, this layer becomes tarnished and needs to be removed and replaced. The video above shows what’s involved in this process—and it’s a very involved process indeed!
Story by Jonathan Nally, editor SpaceInfo.com.au
Images and video courtesy ESO.
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