Why do planes appear to travel so slowly in the sky?

16th May 2013
Why do planes appear to travel so slowly in the sky? (iStock)

Asked by: Peter Young, Forest Row

Our brains judge the speed of objects passing by us through the time taken for them to cross our field of view. Those taking a long time could either be nearby and travelling slowly or faster and further away. And in the case of planes, our brains know that the second interpretation is the right one.