Sir, – Peter Cluskey’s report showing scientific evidence for Rudolph’s red nose (Front page, December 20th) got my colleagues and I, here at the School of Physics, Trinity College Dublin, thinking of the logistics of Santa’s flight on Christmas Eve.
There are around 250 million children in the world that are expecting a visit from Santa. With an average of 2.5 children per house, this means he’ll need to stop 100 million times – assuming there’s at least one good child in every house. When we account for time zones and the rotation of the Earth, Santa will have 31 hours to drop off all the presents. This means he has to make 899 stops per second (or spend ~0.001 seconds at each house!).
If we assume the children he will visit are spread all around the world, he will travel approximately 120 million kilometres – but he only has 31 hours; this means he’d have to travel at at least 3.7 million km/hr – that’s 3,000 times faster than the speed of sound! This brings me to Peter Cluskey’s report – travelling at this incredible speed, the apparent colour of Rudolph’s nose (to any lucky Santa spotter) should be blue. This is due to something called the Doppler effect.
As you can see, there’s a great deal more research needed to understand how exactly Santa gets his job done! – Yours, etc,