20 years on: How Doctor Who's 'The Impossible Planet' and 'The Satan Pit' challenged the Doctor's beliefs

The Doctor has always been a man of science, but these episodes forced him to confront something that defied all rational explanation.

It was a test of faith unlike anything the Doctor had faced before — not faith in a higher power, but faith in his own understanding of the universe.

The Satan Pit remains one of the most ambitious and philosophically rich stories the revived series ever attempted.

Twenty years later, these episodes still stand as a bold exploration of what happens when a man of science meets something that science cannot explain.