Book 8, Question 141
Why Do Many Telescopes Sit Inside Domes with a Slot That Opens?
Many telescopes sit inside domes to stay safe, and the slot opens so they can see the sky! A dome protects a telescope from wind, rain, and dust. The slot opens so the telescope can see the sky.
More fun facts
- When it is open, a large slit in the rotating dome gives the telescope a clear view of the sky.
- The dome turns on the same axis as the telescope but moves on its own, so the slit can line up wherever the telescope points.
- On each of the Very Large Telescope's domes in Chile, the observing slit is 9.50 meters wide and closes with two doors.
- The enclosure blocks wind, and a windscreen in the slit plus louvers in the walls control how much air flows through.
- Temperature differences between the air inside the dome and the air outside have to be kept as small as possible.
- Air near a mirror just 1 degree Celsius warmer than its surroundings is enough to blur the view, which astronomers call dome seeing.
Questions kids ask
Why not just leave big telescopes out in the open?
A dome shields the delicate telescope from wind and weather, and opening only a slit lets it look at the sky while staying protected.