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Why is the bowl of the radio telescope painted white? © iStock

Why is the bowl of the radio telescope painted white?

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The colour of the telescope has no effect on its electromagnetic properties but it does play an important role in regulating temperature.

Asked by: Alan Blackwood, by email

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The colour of a dish doesn’t have any bearing on its electromagnetic properties. However, white reflects sunlight and heat, and that limits how much the temperature of its surface fluctuates. The shape of a radio telescope dish is critical in order for it to perform well as a receiver. Limiting shifts in temperature therefore helps to reduce thermal expansion.


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