The Science of Santa

Santa Claus is coming to town -- for 34 microseconds

"We estimated that there are 48 people per square kilometer (120 per square mile) on Earth, and 20 metres (66 feet) between each home. So if Santa leaves from Kyrgyzstan and travels against the Earth's rotation he has 48 hours to deliver all the presents," he said.

"He has 34 microseconds at each stop" to slide down the chimney, drop off the presents, nibble on his cookies and milk and hop back on his sleigh, Larsson said.