The longest running science-fiction show has been on the air for 50 years, and is still going strong.  One of the many things that keeps "Doctor Who" fresh is that it is constantly evolving.

The Doctor is a Time Lord from the planet Gallifrey who is well over 1,000 years old.  The key to his long life is his ability to regenerate into a new body, which is basically the transition from one actor to the next.

"Doctor Who" was rebooted in 2005, but the new series picked up where the old series left off and we met the 9th Doctor played by Christopher Eccelston, who was only with the show for one year.  He regenerated into the 10th Doctor, played by David Tennant, who had a three-year run as The Doctor. 

Matt Smith then took over as the 11th Doctor, and it was during his run that "Doctor Who" began to grow its American fan base.  After Smith's three-year run, "Doctor Who" fans, known as 'Whovians', were heartbroken when they heard the news that Matt Smith would be leaving the show at the end of 2013.  I'm not gonna lie, I was one of them.

It was announced last summer that British actor, and life-long "Doctor Who" fan, Peter Capaldi would take over as the 12th Doctor.  And while there are mixed feelings on this decision, true Whovians know that the character doesn't change, just the actor that portrays him.  Yes, each incarnation of The Doctor has his own distinct characteristics as each actor puts his own spin on the legendary Time Lord.  But it is still, and will continue to be, the same great character that we met 50 years ago.

Along with unique characteristics, each version of The Doctor has his own costume.  Matt Smith caused a massive jump in bow tie sales because of his costume, and his catchphrase, "Bow ties are cool!"  Yesterday, the Doctor Who Facebook page released the costume for Peter Capaldi's 12th Doctor (pictured above).

Season 8 of "Doctor Who" will not air until later this year on BBC America, so if you haven't seen this hilarious "adult show for kids," you have plenty of time to catch up on all the reruns.  For the Whovians reading this, what do you think of the 12th Doctor's costume?  Do you miss the bow tie and the occasional fez?  Leave your thoughts in the comments below, and watch the regeneration from the 11th Doctor to the 12th below.