Attention all sections Alpha: we're on a collision course with a fantastic event - Space: 1999's 50th anniversary!

We asked you to pick your favourite episodes of Gerry and Sylvia Anderson's classic sci-fi TV series. We've collated your answers and are kickstarting the series' 50th celebrations by bringing you deep-dive listicles on your chosen episodes!

Our latest entry sees Moonbase Alpha encounter one of its most fantastic experiences in the terror-ridden depths of outer space. The Moon finds itself locked onto an unstoppable course with a colossal black sun. Efforts to protect the base from its gravitational grip prove futile, but the awe-inspiring secrets that lurk within this grandiose phenomenon are beyond human comprehension. 

Let's examine 10 fascinating facts about Black Sun!

10. Two-hour odyssey

Black Sun was the only fully realised script of Space: 1999 written by David Weir. His other contribution to the Space: 1999 canon was an early draft of Guardian of Piri, provisionally titled Nobody's Perfect, but the finished screenplay was written by Space: 1999's story consultant, Christopher Penfold. Weir's original draft of Black Sun ran to nearly two hours' worth of material and had to be vastly trimmed down!

9. Chaos from Katzin

Space: 1999's debut episode, Breakaway, was plagued by a needlessly prolonged production shoot, brought on by director Lee H. Katzin's overly meticulous approach to filming. Sure enough, he evidently didn't learn from the follies of Breakaway, as Black Sun similarly greatly overran its production schedule. Ray Austin would step in to direct Ring Around the Moon, the next episode supposedly lined up for Katzin to direct, but following completion of Black Sun, Katzin was dismissed from the series, his contract terminated.

8. Black 'hole'?

Space: 1999 has weathered some severe criticism over the years for its scientific accuracy - or rather, its lack of! Such criticism hasn't been entirely just, and speaks more about science fiction's embracement of imaginative looseness of depicting science than any crime Space: 1999 specifically commits. However, Black Sun does rather bear a glaring bump in its depiction of space phenomena that's still not strictly an error. The phenomena in the episode is consistently referred to as a black sun, when really its depiction is more akin to a black hole. Nevertheless, the term black sun would appear again throughout the series - an interesting note of consistency.

7. Cast and crew favourite

Whatever scientific accuracies the episode may play fast and loose with, its dramatic thrust of the Alphans accepting what appears to be their final fate, only to experience something magical when passing through the sun itself, has enabled the episode to remain a firm favourite with its cast. Gerry Anderson himself recounted the episode as a highlight of the series for him. "We had some very, very good performances (in Year 1)," Gerry recalled in the 1990s. "I can't remember if it was in Year 1 or 2, where Koenig and Victor Bergman were aged terribly...". Even if Gerry couldn't place his finger on the episode's title, its fantastic sequences of the Alphans being propelled through the black sun itself clearly held a lasting impact.

6. ITC's wrath

Unfortunately, one particular viewer who wasn't impressed with Black Sun just to happened to be Space: 1999's chief financial backer. Abe Mandell, head of ITC New York, was furious at witnessing Black Sun. He was not at all taken with the episode's surreal, metaphysically intellectual thrust. Following production of Black Sun, all scripts written for Space: 1999 would now have to be telefaxed to ITC New York for final approval, which slowed the series' entire production into a glacial pace and was the reason for Penfold's eventual departure from production of the first series.

5. Super Space Theatre

Black Sun and Collision Course, two thematically connected episodes depicting Moonbase Alpha journeying into the heart of the galactic unknown, were combined into the 1982 compilation film Journey Through the Black Sun. While Destination: Moonbase Alpha and Alien Attack preceded this third compilation film by several years, Journey Through the Black Sun was, in fact, the first Space: 1999 compilation film to be specifically released under the Super Space Theatre banner. 

4. Maybe There novelisation

The earlier screenplay of Black Sun would still find an eventual renewed lease of life in Maybe There: The Lost Stories from Space: 1999 by David Hirsch and Robert E. Wood. Maybe There features several other novelisations of scripts that were either earlier versions of finished screenplays or finished episodes entirely. 

3. Character traits

As the Moon hurtles towards a seemingly grim demise, we see several personality traits emerge from several Alphans. Computer expert David Kano's fondness for chess yields the rarely seen pairing of himself with medical specialist, Bob Mathias. Kano's love of chess would emerge in further episodes, an appropriately logical game for someone of Kano's professional role on Moonbase Alpha. Elsewhere, controller Paul Morrow's guitar capabilities provide a softly tuned respite as to the oncoming apocalypse.

2. Rare speaking role for Natasha

Speaking of lesser seen character interactions, Main Mission Operative Tanya Aleksander is given a rare and brief but still welcome speaking role when sitting in with Paul's guitar playing. Suzanne Roquette portrays Tanya in 22 of Year 1's 24-episode run. Tanya is one of several background Alphans who help to enliven the Main Mission set, but this romantic suggestion between her and Paul would become enhanced in Powys Media's spin-off novel The Foresaken, in which she and Paul would depart Alpha for a new life on the planet Pyxidea.

1. Mysterious Unknown Force

Black Sun is the first episode of Space: 1999's first series to greatly suggest that Moonbase Alpha's odyssey across the stars may not be as accidental or unforeseen as the events of Breakaway imply. Koenig and Bergman's exchange with 'god' seemingly confirms that Moonbase Alpha's journey is a deliberate act in the hands of some unseen cosmic deity and that their journey is destined to allow humanity to prosper across the universe. Collision Course and The Testament of Arcadia are the other two episodes to hint at this events. However, the MUF was never planned prior to the series' production. Instead, it gradually became a natural inclusion to the series' thematic ideas as writing on the series progressed. 

Whatever cosmic mysteries Koenig and Bergman experienced when travelling through this bizarre entity, Black Sun's unshakable status as one of Space: 1999's most successful creations remains entirely justified. It's a surreal, haunting, doom-laden and ultimately euphoric adventure for the people of Moonbase Alpha.

Be sure to check out our previous listicles counting down several intriguing facts about several fan favourite Space: 1999 episodes - The Last Sunset, The Bringers of Wonder and Breakaway!

Sign up to the Anderson Entertainment newsletter to receive all the latest Gerry Anderson news, exclusive releases and more transmitted direct to your inbox!