Doctor Who turns 50 on November 23. So, what exactly continues to appeal to viewers about the series?

This has been a week of anniversaries. While Calvin and Hobbes turned 28 a few days ago, the wildly popular and much-loved television series Doctor Who turns 50 on November 23, with the BBC airing a 75-minute-long special to commemorate the occasion. The Doctor himself is anywhere between 900 and 1,200 years old (relatively speaking). The series chronicles the adventures of the eponymous time-travelling alien and his human companions.

Premiering the day after JFK was assassinated, it went on to become one of the U.K.’s longest running shows — spanning 26 seasons — until 1989. After a 16-year gap, the series was picked up again in 2005 and has completed seven seasons so far. It has been ever-present in the world of pop-culture over the years. So what’s the secret behind such a fantastic run?

Of course, there are a number of other good shows from the U.K. — one can even argue that what British shows lack in budgets and star power they make up for through great acting and intelligent writing — not many are as well recognised as their American counterparts.

And then there’s the number of episodes to consider: Lee Mack’s hilarious sitcom Not Going Out has only six to eight episodes a season as opposed to the 24 or 25 that is standard across the Atlantic. BBC’s critically acclaimed Sherlock has only had six episodes in the two seasons thus far. Doctor Who, however, is not found lacking in that department.

Apart from the various spin-offs, movies and plays, the series alone has completed more than 800 episodes. Even to hardened veterans of television trumps (where players get together and compare various shows and number of episodes they have watched, to determine the ultimate winner / loser), that is weeks spent glued to the screen with little or no sleep. If only they could have the TARDIS to help them manage their time! But I digress: one possible reason for this high a number may be the flexibility that the premise allows — there is no limit to the number of stories one can weave around a centuries-old Time Lord with a penchant for 20th and 21st Century Britain.

By giving the alien the ability to regenerate into a new body, the writers have cleverly sidestepped any difficulty in re-casting the lead role. And while this was originally done to solve the problem of ageing actors, it has inadvertently led to the show staying fresh. There have been 12 Doctors so far and a 13th is in the offing. Each incarnation has specific and individual characteristic traits, catchphrases and quirks. This allows incoming actors freedom to experiment and make the role their own. The audiences too, welcome this approach — the recent announcement that Peter Capaldi has been roped in to play Doctor No. 13 has received positive public response.

But eclectic story arcs and clever casting gimmicks alone cannot be the reason for the show’s phenomenal success. The sheer volume of heart that the show oozes is what sets it apart (indeed, the Doctor himself has two!). Even though he is an alien with little regard for the space-time continuum, he isn’t an ultra-powerful benevolent demigod like Superman. He bumbles through various situations with no clear plan of action and yet seems to emerge victorious at the end of the day. His awkwardness and his flawed persona endear him to us. So do his relationships with his human companions.

Deep down, the show is about just that — the joy of relationships, the bridges crossed and lessons learned while growing up and learning to face one’s own mortality. No wonder audiences of all ages seem to enjoy the show equally. And so, even though 50 earth years of linear time have passed, this Time Lord has yet to show any signs of tiring.