When's Santa coming? Online Santa trackers are back again this year, for parents having to answer that perennial question.

Continuing a 60-year tradition, the North American Aerospace Defense Command (NORAD) is again hosting its annual "NORAD Tracks Santa" event Thursday in partnership with Microsoft.

As legend has it, the tradition started in 1955 when a typo in a Sears ad had kids calling a number they thought would give them a chance to speak to the jolly old elf. Instead, they reached the hotline of NORAD's predecessor, the Continental Air Defense Command. Instead of turning them away, Col. Harry Shoup, the operations director at that time, decided to keep the holiday spirit and play along. Using radar screens, he provided details of the location of Santa's whereabouts. NORAD later took up the tradition in 1958.

As it has done in previous years, NORAD is giving Santa trackers many options for keeping up with Santa's location. Followers can call 1-877-HI-NORAD (446-6723) or email noradtrackssanta@outlook.com. NORAD is also offering Santa tracking apps on iOS, Android and Windows Phones. Microsoft's Cortana will also answer questions about Santa's position, as will the OnStar in-car navigation system.

And this year, visitors to NORAD's website can also watch Santa prep for his flight via NORAD's "Santa Cams" that will stream videos of Santa throughout the world.

Besides NORAD, Google is also offering its annual Santa Tracker this year, as part of a bigger site that the company has had up for a few weeks. There, kids can track Santa and learn about the way people celebrate Christmas across the world. The company has its own Santa tracking app for Android, using its Google Maps technology.

Parents using both services may notice that Santa's position varies a bit between the services -- but they may also notice that the jolly old elf always seems to be projected to make roof-fall in their neighborhood around bedtime.