This Is Why Star Trek Captain Picard (Patrick Stewart) Rang The Bell At Twitter's IPO

Twitter's much anticipated IPO happened today but it wasn't Twitter's famous cofounders or CEO that rang the opening bell at the New York Stock Exchange to commence trading.

It was Patrick Stewart, an actor known for playing Captain Picard on the television series (and associated movies) "Star Trek: The Next Generation."

What the heck was he doing there?

Twitter says its site is all about the people who use it, so it decided to let a few notable users ring the bell.

Sir Patrick Stewart (@SirPatStew) is a big user of Twitter with 723,000 followers. He told CNBC that Twitter helped changed his career. "It has changed the perception of who Patrick Stewart is."

The reason for the choosing users was explained in a Tweet by the NYSE Euronext (and retweeted by @Twitter):

.@twitter owes success to its users, so gives #NYSEBell to @sirpatstew, @vivienneharr & @bostonpolice #TwitterIPO pic.twitter.com/f5eqc0Xjht

- (NYX) NYSE Euronext (@NYSEEuronext) November 7, 2013

There were two other people who rang the Twitter bell. The girl is Vivienne Harr, (@vivienneharr) a Bay Area fourth-grader who kept a lemonade stand for 365 days to raise awareness of child slavery across the globe. Twitter helped her gain national attention. She has 22,000 followers.

Twitter also invited the Boston Police, (@bostonpolice) who used Twitter after the Boston Marathon bombings. They sent Cheryl Fiandaca to represent them, the department's Bureau Chief of Public Information.