I’ve calculated Santa’s speed on Christmas Eve – and this is what it would do to Rudolph’s nose

By Laura Nicole Driessen, Postdoctoral Researcher in Radio Astronomy, University of Sydney

With billions of children around the world anxiously waiting for their presents, Father Christmas (or Santa) and his reindeer must be travelling at breakneck speeds to deliver them all in one night.

But did you know that light from an object travelling at high speeds changes colour? This is thanks to what’s called the Doppler effect – the way speed affects the length of waves, such as sound or light.

When light changes colour due to speed, we call it redshift or blueshift, depending on the direction. If we could catch the colour of Rudolph’s famous red nose with one of our…

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