Wolfram Alpha, the online search service launched two years ago, now lets inquiring minds in the United States find out what flights happen to be overhead at any given moment.

Typing "flights overhead" into a Wolfram Alpha query box is rewarded with information about airplanes above, including altitudes, distances, aircraft types, and which airlines are operating them.

"You'll get information on aircraft that should be visible to you, assuming a clear sky and unobstructed view," Wolfram Alpha said Friday in a blog post at its website.

"At one time or another, we've all looked at a jet flying high overhead and thought 'I wonder where they're headed?'"

If people are using smartphones, Wolfram Alpha results will be based on latitude and longitude information provided by location-sensing capabilities in devices.

Otherwise, the service will work with whatever location information is supplied by Web browsing software.

Wolfram Alpha launched in May 2009 as a search engine that delivers factual answers to online queries instead of links to Web pages.

The curated answer engine uses mathematical formulas to scour the Internet for information and natural language recognition technology to figure what queries are aimed at finding out.