In the eyes of Time magazine's managing editor, Richard Stengel, WikiLeaks founder Julian Assange is a here-today, gone-tomorrow phenomenon, but Facebook founder Mark Zuckerberg's success will last the ages.

Stengel defended his magazine's choice of Zuckerberg as 2010's Person of the Year in an interview with Yahoo's Michael Calderone.

"Assange might not even be on anybody's radar six months from now," Stengel said, noting that "there is no Julian Assange without Bradley Manning," in reference to the Army private accused of leaking 260,000 State Department cables to WikiLeaks.

"I think Assange will be a footnote five years from now," Stengel said.

By contrast, Zuckerberg's Facebook shows that "something is going on deep down in the human character that's changing and evolving," Stengel said. "Is there a bigger story than that? I don't think so."

Time came in for some criticism over its choice of Person of the Year, especially given that Assange won the magazine's online poll, garnering about 20 times more votes than Zuckerberg.

Some critics pointed out that Time seems to be behind the times in recognizing Facebook, which exploded as a phenomenon in 2006 and 2007.

"Time just named its Person of the Year 2007," Tweeted comedian John Hodgman.

Some took a more aggressive tone, accusing the magazine of cowardice in picking a less-controversial figure than Assange. Slate editor-in-chief Jacob Weisberg called the decision "gutless."

But Time's decision may have been as simple as following a consumer fad. Calderone notes that 2010 was the year that Facebook exceeded 500 million users, and saw its profile raised by the release of The Social Network, the Zuckerberg bio-pic that has grossed close to $200 million worldwide so far.

"All of that made me think this was his year," Stengel said.