Troughton was the first actor to put the idea of the Doctor's regeneration - a transformation which saw essentially the same character re-incarnated with a very different persona in another's body - into practice.
It is often considered as the turning point in the evolution of Doctor Who, becoming a critical element for the longevity of the show.
The Second Doctor's time came to end when he broke the Time Lord's laws of non-interference. He was sentenced to exile on 20th century Earth, forcing him to regenerate in the process.
Fun fact: Troughton commanded a gunboat in the second world war.
Tools designed to ensure computer code in smart cars does not crash has been inspired by hungry penguins.
The rounded sleeping capsules send guests drifting into ocean before arriving on desert island by morning.
Sitting on the saddle activates the part of the brain responsible for learning, a study has claimed.
Scientists are appealing for more people to donate their brains for research after they die.
Life on Earth may have arrived from Mars on an asteroid, scientists have claimed.
Lunar mission scheduled at the end of 2017 could find out if beer can be brewed on the moon.
A bottle used to teach children how far litter can travel ended up on Scottish beach after 8,700-mile journey.