Santa Claus is comin' to town – and NORAD is on it.
The jolly ol' fellow has already made his first stops in Australia and will be stopping at homes around the world in time for Christmas morning.
Using a radar system called the North Warning System, NORAD is able to tell when Santa Claus leaves the north pole. NORAD's satellites have infrared sensors that can see heat, and Rudolph's bright red nose gives off an infrared signature that the satellites can detect with no problem.
However, only Santa knows his route. NORAD can't tell you exactly when Santa will arrive at your home, but in most countries he arrives between 9 p.m. and midnight when most children are asleep.
Children around the world can follow Santa's journey at or by phoning 1-877-HI-NORAD.
This year, NORAD is celebrating 69 years of tracking Santa along his journey. NORAD, the North American Aerospace Defense Command, is a joint Canadian-U.S. organization.
NORAD's predecessor, Continental Air Defense Command, first began tracking Santa in 1955, but it was entirely by accident.
In 1955, a young child accidentally dialed the unlisted number of Continental Air Defense Command after seeing a newspaper ad telling children to call Santa. Col. Harry Shoup answered the phone and instructed his staff to check the radar for Santa making his way south, unknowingly beginning a tradition.