Christmas and science may not appear to have much in common but a good knowledge of science is what has allowed Santa Claus to keep the Christmas spirit alive for so many years. Science is what allows Reindeer to fly and for all those presents to be delivered in one single Christmas Eve.
If we assume that Santa has to travel 510,000,000km on Christmas Eve, and that he has 32 hours to do it (Travelling east to west with the Sun, maximising his available night-time, Santa has about 32 hours to work with assuming children sleep for eight hours, he has 24 hours plus those eight to finish), then Santa will be travelling at 10,703,437.5km per hour (1,800 miles per second) which is incredible. The fastest-moving human-made object in history is the space probe Voyager 1 which manages a rather less impressive 10.8 miles per second. Assuming he never stops: some sort of sleigh-mounted present-launcher will be required to shoot gifts down chimneys while moving. The guidance system will have to be quite impressive, to avoid accidentally showering Afghan wedding parties with extra presents.
There are roughly 2 billion children worldwide. However, assuming Santa doesn’t visit the children of Hindu, Muslim, Jewish, atheist and so on parents, that leaves the 35 per cent or thereabouts whose parents consider themselves Christian. That’s still an impressive 700,000,000 children in a night.
If each child’s present has a boxed weight of 1.2kg that’s a total of about 840,000 tonnes of toys, which will require 5,600,000 reindeer to pull. Given each reindeer weighs around 272kg (600lb), the whole procession (assuming a weightless sleigh) will have a mass of 2,363,200 tonnes when standing still. Learn more here or here.