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This entry is about the episode. For information about the phenomenon, see Black Sun (Phenomenon)


“Do you have any idea what'll happen to us inside the black sun?”
“Whatever it is, I just hope it's interesting.”


Terror in Outer Space confronts the breakaway moon personnel when on a collision course with an all-devouring "black sun."[2]


An asteroid is detected in the proximity of Alpha, but all indications suggest that it poses no threat. Suddenly Computer raises the alarm. The asteroid is now on a collision course for Alpha. With no time to destroy it, the Alphans brace for impact. The asteroid narrowly misses the base as it's trajectory changes again. The Alphans watch in amazement as it stretches and is destroyed by unseen forces. It becomes apparent, that whatever altered the course of the asteroid, has now changed the course of the Moon. They are heading right into it.

Act One[]

An Eagle is dispatched to investigate the phenomenon. Astronaut Mike Ryan, reports back to Main Mission, stating that none of his sensors are bouncing back, and he can get no readings. He asks to move closer to try to get more information. Victor finishes his calculations and rushes to Main Mission with his findings. Koenig tries to recall Mike, but it's too late. Mike's Eagle is caught in the gravitational forces of the black sun. Even with his anti-gravity screens at maximum, and his engines at full power, he cannot escape. The Main Mission crew watches in horror as his ship stretches, and is destroyed on the big screen.

Koenig calls a command conference to discuss the situation. After Computer confirms that it is a black sun, Paul asks Professor Bergman if they can avoid it. Victor explains that the gravitational forces are so immense that nothing can escape it, not even light. But he does have a plan. He explains that he will alter the gravity towers to generate a force field that will reverse the crushing force of the black sun, using its own force to protect Alpha. While there are no guarantees, it is their only hope.

Act Two[]

Later, Helena is looking for John, and learns he is outside with Victor. Paul directs her attention to the screen. They are ready to perform a test on the force-field. Koenig gives Paul the command, and the force-field is activated. Beneath the supposed safety of the energy screen, Koenig orders Alan to fire his Eagle's laser at them. The beam is blocked by the force-field, and Koenig and Bergman jump for joy. Back inside Alpha, Helena chastises them for their stupidity. Victor replies that Computer gave them a ninety-eight percent chance of surviving the test. They go on to explain that it was all done for moral, and proved nothing. That realistically, the chances were slim they would survive the encounter with the black sun. When Helena asks the point of the force-field, Victor says "the same point that prevents you from giving up on a patient until he's dead." Victor leaves, and John tells Helena that he has left one Eagle intact to use as a lifeboat, to insure the survival of a small group of Alphans.

The temperature starts to fall on Alpha as the black sun starts draining off their energy. In order to save power to operate the force-field when they need it most, energy conservation plans are drawn up. Victor informs Kano that Computer will have to be deactivated. Paul tells Koenig that The Moon is being drawn into the black sun faster than originally calculated, as it is impossible to predict how much mass is available to the black sun in the sector. Koenig must activate the force-field in order to slow the Moon down enough to give time for the "life boat" to be launched. Victor is in the Main Power Unit when a warning light goes on, indicating a fault. When Victor tries to fix it, he is electrocuted.

Act Three[]

Luckily his artificial heart saves him, and he recovers in Medical Center with no ill effect. Supplies are being loaded onto the survival ship as quickly as possible, while repairs are made to the force-field. The force-field is activated to check the repairs and slow the Moon's momentum towards the black sun. Alan confronts Koenig about the survival ship and wants to know why he wasn't told. He says that he should be one of the six because if anyone can get them somewhere, he can.

Koenig makes his announcement to the base about the survival ship and lists those, selected by Computer as the most likely to ensure the survival of mankind in space, who will be on the Eagle: Alan Carter, George Osgood, Toshiro Fujita, Helena Russell, Sandra Benes, and Angela Robinson. They gather in Koenig's office where he tells them they will lift off in twenty minutes. They all leave to prepare, except Helena. She tells John, that she's not going. He tells her the list is final, and that this is no time for noble gestures. She says it's not a noble gesture and asks what difference does it make if she dies in space or on Alpha. Koenig replies that it matters... to him. The crew board and the Eagle lifts off, heading away from the black sun. The force-field is turned back on, and the remaining Alphans await their fate.

Act Four[]

Victor joins Koenig in his office, bringing him a spacesuit to keep warm. He asks John if he ever considers how and why they have survived, telling him that he ran the probability through the computer, and it almost blew up. The odds are almost infinite against them having survived so long. Koenig asks if he's referring to God. Victor replies that being a scientist, he doesn't know anything about God. A "cosmic intelligence" is more what he had in mind, but supposes we all believe what we want to believe. Koenig relieves Paul from his duties in Main Mission, and he and Victor move into the empty control center.

Victor brings out a bottle of 60-year-old brandy. They toast, John: "To everything that might have been", and Victor: "To everything that was." Around the base, the Alphans await the Moon's entrance into the black sun in various ways, some playing cards, chess, etc. Paul plays his guitar in his quarters. Tanya appears at his open door and asks if she can share the music with him. He nods, and she sits down with him. The Moon enters the black sun.

In Main Mission, John and Victor become transparent. Amazed that the force field held, they notice that they no longer feel the cold. The survival Eagle and its crew experience a similar effect, despite the distance it put between itself and the black sun. John and Victor age suddenly and find themselves in a place of light. They can hear each other's thoughts. They hear a female voice. When asked who she is, she answers "a friend". John surmises that every star is just a cell in the brain of the universe. The voice says that's a lovely way to understand it. As the Moon exits the black sun, she tells them it was good to have known them. They find themselves back on Alpha, no longer suffering from the power drain of the black sun, and now somewhere on the other side of the universe.


Everyone returns to duty. As they give up hope of ever seeing the survival ship again, it appears on the big screen. A cheer goes up in Main Mission, and they race to greet the Eagle at the landing pad. John asks if they followed the Moon into the black sun. Alan tells him they went in the opposite direction. When asked how they found Alpha again, Alan says he's an astronaut not a philosopher, Helena suggests that something brought them home.[3]


First draft script November 1973. The script was overlong—Christopher Penfold estimated there were 120 minutes worth of story.

Second draft script 5th December 1973.

Shooting script 21st January 1974, revised 24th January (by Christopher Penfold)

Filmed 31st January to 21st February 1974. Filming took three-and-a-half weeks instead of the allotted two weeks; because of the over-run on this and Breakaway, director Katzin was not asked to direct any more episodes as he had been contracted to do.

The episode was nevertheless a favorite with all the cast and crew. However, Abe Mandell was incensed and stated they might as well close down the entire show; the episode was impossible to understand. According to Martin Landau, "It was jazzed up because some people said it was too slow." In fact, the final episode is very close to that scripted. Subsequently all scripts had to be sent to the US to be vetted.

Edited into the 1982 compilation movie Journey Through The Black Sun[2]


  • Int. Main Mission
  • Int. Command Office
  • Int. Victor's Quarters
  • Int. Computer Room
  • Int. Main Power Unit
  • Int. Alpha Corridor
  • Int. Travel Tube
  • Int. Eagle Pilot Section
  • Int. Eagle Passenger Section
  • Ext. Moon Surface
  • Int. Black Sun Void[2]


There are five front-shots of the Eagle showing the astronauts.

The explosion of Ryan's Eagle is a little too small and obviously superimposed over the model.[2]


Black Holes were first theorised in 1796 by Pierre Laplace, but named as such in 1967 by physicist John Wheeler. The episode may have been inspired by Professor John Taylor's 1973 book "Black Holes: The End of the Universe?". The term black hole is the standard name since about that time; older terms include frozen star, black star, and black sun, which persisted into the early 1970s.

"A hatful of the stuff can weigh more than several Alphas." Actually, a black hole has a singularity as its centre point of infinite density. It would weigh more than several moons.

Light from behind a black hole is bent around the event horizon; this is a region around the singularity where the escape velocity is equal to the velocity of light. The episode is accurate in its portrayal of a black circle with a rim of stars.

The intense gravity of a black hole creates so-called tidal effects, stretching and tearing apart objects as their near side is subject to much more gravity than the far side. The stretching of the Eagle and asteroid is therefore accurate. However, the Moon should also be destroyed by the same tidal forces.

Super-massive black holes—which can be found in the centre of galaxies such as the Milky Way—are so large that tidal forces are much weaker. Theoretically, an object could enter the event horizon of a supermassive black hole without being torn apart.

Note the force field does not cover the outer-most areas of the Moonbase.[2]


Alpha Personnel: 1 fatality: Mike Ryan.

Kano also plays chess in Dragon's Domain. They use real chess pieces here (in Dragon's Domain the pieces are flat squares with symbols).

Although under-developed, there is a suggestion of a triangle-relationship between Paul, Sandra, and Tanya.

Alpha Technology:

The artificial gravity system is explained by Bergman (we see the gravity towers for the first time, modified from the towers seen in Nuclear Disposal Area 1 in Breakaway). They are enhanced in this episode to provide defence screens used in many subsequent episodes (notably The Last Enemy). Koenig and Bergman bounce in low gravity in the immediate vicinity of a tower...

First use of Victor's mechanical heart (also used in Guardian of Piri, Force of Life and The Infernal Machine).

First use of Computer Room (also seen, slightly revamped, in Space Brain).

First use of the Main Power Unit (also seen in Earthbound). This set is a revamp of Koenig's office.

First use of the hexagonal Alpha storage boxes (also prominently featured in The Last Sunset).

Only use of the Alpha News Service.

First use of jackets, used prominently in Year 2. These silver jackets reappear in Testament of Arkadia.

Eagles: Eagle 1 (Ryan, destroyed); 5 (lifeboat); Alan's laser Eagle. An empty pallet pod is seen on the launch pad alongside the lifeboat Eagle in one shot.

Planets: None.

Aliens: Cosmic Intelligence in Black Sun.

Errors: This interior scene shows the Eagle docked to the starboard side, yet external views show the Eagle docked from the port side (the exception is the liftoff). Note the wooden base of the box is visible in some shots.[2]


Footage of Victor doing calculations on a glass panel in his room was reused in Dragon's Domain.

There are a few unused shots in the This Episode sequence.

This is the universal favourite with all the cast. Says Martin Landau: ""Black Sun was one of my favourite shows. That was shot early on in the first season. We thought that was the direction the show was to take. We had relationships, humour, a bunch of us, and music... beautiful! Unfortunately, you didn't see the version I liked. It was jazzed up because some people said it was slow. That was a period of finding out. That was the direction Barbara and I wanted the show to go in. Gerry also. We watched Black Sun and said it was really marvelous and it's what Space needed. It's the direction the rest of the show should have." (1978 convention).

The suggestion of conflict between Bergman and Kano was more overt in the script; Victor is still quite gloating when he states "Computer could do with a rest."

Alan's speech, "I care about I die...", does not work; it comes across as cowardice or whining instead of an assertion of hope.

Sandra faints when Ryan is killed; Zienia Merton disliked this clichéd behaviour and she became a stronger character later in the series (although fainting women reappeared in The Metamorph). Later, as Paul sees her off, there is a suggestion of a new romance between them which is realised in The Last Sunset.

Marc Zuber appears as a Main Mission Operative in this episode. He later appears in Brian The Brain as a security guard.

In 1997, the documentary Equinox on UK Channel 4 showed clips of this episode as part of a documentary on black holes.[2]


The episode was intended to be shown very early in the series' run (ideally as episode two), as the conclusion serves as a device to get the Moon out of the Solar System and hundreds of light years from Earth into regions of space where stars and planetary systems are much closer together. Unfortunately, on original transmission Black Sun was shown as episode ten, by which time viewers had already seen the Alphans visiting other star systems and habitable planets - consequently, the series suffered from adverse criticism for scientific inaccuracy. The episode also introduces the concept of an omnipotent being who is guiding the Alphans' journey towards some unknown destiny.

Some of the themes of this episode were later explored by Gerry Anderson and Johnny Byrne in the 1975 TV pilot The Day After Tomorrow.


Season 1
Breakaway I Earthbound I Black Sun I Missing Link I Voyager's Return I Matter of Life and Death I Ring Around the Moon I The Last Sunset I Alpha Child I Death's Other Dominion I Force of Life I Guardian of Piri I The Troubled Spirit I The Last Enemy I Collision Course I Dragon's Domain I The Full Circle I Mission of the Darians I End of Eternity I War Games I The Infernal Machine I Another Time, Another Place I Space Brain I The Testament of Arkadia
Episodes are listed in the order suggested by Andrew Kearley.