# Calculations reveal Santa travels at 0.5% the speed of light

University of Leicester students have worked out just how fast Santa Claus has to travel to deliver all of his presents on time

On Christmas Eve night, Santa Claus and his reindeer fly around the world delivering gifts to millions of children in preparation for Christmas Day. But just how fast does Santa Claus have to travel in order to achieve this amazing feat?

Well, three University of Leicester physics students, Arcchana Gajendran, Shannon Madden and Ridda Mahmood have calculated just that.

They started their calculations by estimating the number of households Santa would need to visit. With about 715,000,000 Christian children on the planet and assuming an average of three children per household, Santa Claus would need to visit 238,000,000 households.

The students then calculated how long Santa Claus would have to deliver his presents. They assumed a travel time for Santa Claus of 12 hours, although taking into account time zones and presuming he travels from east to west, he would have an additional 24 hours to complete the task.

Using these figures, Santa Claus would have to travel at a speed of 1.56 x 106 m/s. That’s about 0.5% the speed of light.

The students also derived the size of the aerofoils Santa would need in order to stay airborne. They found this to be approximately 1.26 x 10-3 m2.

Ridda Mahmood said: "The value itself is a rough estimate given the limitations of a two-page article, but having aerofoils of a few millimetres squared gives a rough estimate of how much magic Santa uses."

Shannon Madden said: "We came up with a seasonal question we thought would be fun and festive to investigate, although we know there are some limitations."

Future work might also consider how long Santa spends at each household, commuting time to and from the North Pole, and the acceleration potential of the sleigh.

However, the students believe that this work provides a useful insight into the effort Santa Claus and his reindeer have to go to in order to keep more than 238 million children happy on Christmas morning.

The students presented their findings in a paper for the 2017 Journal of Physics Special Topics, a peer-reviewed student journal run by the University’s Department of Physics and Astronomy. The student-run journal is designed to give students practical experience of writing, editing, publishing and reviewing scientific papers.

Course leader, Dr Mervyn Roy, a lecturer in the University’s Department of Physics and Astronomy, said: “The aim of the module is for the students to learn about peer review and scientific publishing. The students are encouraged to be imaginative with their topics, and find ways to apply basic physics to the weird, the wonderful and the everyday.”