I’ve already written a little about the WIYN telescope itself, but equally revolutionary at the time was its enclosure. Domes used to be designed to keep as much of the external world out as possible, isolating the telescope from the turbulent air outside; the high point of this design might be represented by the Kitt Peak 4-m, standing high above the ground in an effort to get above the turbulence.

If you look closely at the dome, though, you might spot a series of small shutters. These were added afterwards, once it had been realised that opening your telescope to the air made a lot of sense; a smooth air flow across the mirror is easier to establish than completely still air beneath an open dome slit, and doesn’t interfere with the quality of astronomical images. That’s the thinking behind the initially shocking design of the WIYN ‘dome’:

The large holes in the side allow the wind to pass through, creating stable conditions inside the dome. (That’s the theory; last night we had to shut the panels because the wind was strong enough to noticeably shake the telescope.) There are other advantages too, of course; panels of steel are cheaper than beautifully shaped domes. It may not be aesthetically as pleasing, but it works.