Whilst this episode has some interesting ideas like giant bacteria and the moon being an egg they simply have no place in Doctor Who and would be better suited to a sci-fi B movie. For this story to make any sense at all you basically have to ignore every single episode that has come before and likely every one that will follow. As well as basic science of course.
In fact I can't even be bothered to leave a proper review. Instead, like most everyone else on here, I will just list some of the things that were wrong with it in the hope that the writers read it and learn from their terrible mistakes. Given that the core concept of the episode was the public sending messages to a small group of people that seems rather apt.
First of all the giant bacteria. I'm sure science puts a limit on how large a single celled organism can actually be but I'll let that one slide. However them behaving exactly like spiders to the point where they even create webs? Why would they possibly evolve this behaviour if they live off larger species like a parasite? Since the episode didn't show any possible prey for them besides humans they wouldn't be catching anything anyway. Then comes the question of why the kid would possibly spend ten minutes kitting up in a spacesuit and then decide to grab the bottle of disinfectant to take with her onto the surface of the moon. If that scene had taken place on the Tardis it would have at least made sense. Hell if they had just established her to be an obsessive compulsive germaphobe it could have been lazily written off. Then they find the body of their crewmate in direct sunlight despite establishing that the creatures avoid it which did make sense at the time given that UV light kills bacteria. Later they are also crawling all over the surface in the light, so much for that idea then.
Then the creature itself. The premise of it having been inside the moon the entire time is completely ludicrous as such a thing would have been noticed. If the story had taken place around an alien planet yet to discover spaceflight then the idea would have been acceptable. When it hatches the surface of the moon just turns to harmless rubble instantly for whatever contrived reason the writers failed to think up. Anyone who has seen any kind of fish/insect/lizard/bird hatch knows full well that most of the shell remains intact. Trying to apply logic to the situation is fairly pointless though as it is also never made remotely clear where the extra mass the moon creature is acquiring is coming from. Had they said the creature was born with a wormhole in its stomach that was sucking in matter from elsewhere they at least could have tried to justify the idea. I sort of got bored of watching but it seemed to suggest it was the bacteria multiplying that caused the mass gain which still solves nothing as they could only have fed on the creature itself. At the end it simply flies off with what appear to be dragon wings. At least the star whale seemed to move via some as yet unknown propulsion method and not by simply flapping its wings in a vacuum...
The most ludicrous part of all however is naturally the end where the beast lays a 'new moon' egg which looks completely different to the moon and so screws with all past episodes that show it in the future. The earlier 'hologram' line was clearly devised to cover this but simply fails frankly. Worse of all though is the ridiculous idea of a newly hatched creature laying an egg larger than itself. The episode simply cuts to the new moon being in the sky and no one seems to question the sheer impossibility of this scenario.
The Waters of Mars storyline is also rendered seriously tenable after this one. As someone else pointed out this would mean that the human race put together a viable Mars colonisation programme in just a decade. It also means that after enduring major catastrophe on Earth they decided to spend fortunes flying to Mars instead of, you know, fixing stuff at home. The crew on the Mars mission are also dumbfounded as to how the Doctor arrived on the planet, which was a logical reaction at the time. Now though we have to assume that the astronaut who survived the mission and returned to Earth didn't bother telling anyone what had happened or how she got home. The only way anything that happened in this episode can possibly make sense is if the end of this series has some kind of major time reset event like that which occurred with the Master, or if it is revealed to all be a simulation or something.
All in all an episode which simply has to be completely ignored in order to continue enjoying the programme. What alarms me however is why this episode was ever put into production in the first place. They must have known at the time that it made absolutely no sense and didn't remotely fit in with other Doctor Who episodes. It concerns me now whether future episodes will ignore this one totally or try to justify the things that happened in it (like showing the new moon around Earth in future stories). Either way they must be really scraping the bottom of the barrel if this is the best writing they could find.
In fact I can't even be bothered to leave a proper review. Instead, like most everyone else on here, I will just list some of the things that were wrong with it in the hope that the writers read it and learn from their terrible mistakes. Given that the core concept of the episode was the public sending messages to a small group of people that seems rather apt.
First of all the giant bacteria. I'm sure science puts a limit on how large a single celled organism can actually be but I'll let that one slide. However them behaving exactly like spiders to the point where they even create webs? Why would they possibly evolve this behaviour if they live off larger species like a parasite? Since the episode didn't show any possible prey for them besides humans they wouldn't be catching anything anyway. Then comes the question of why the kid would possibly spend ten minutes kitting up in a spacesuit and then decide to grab the bottle of disinfectant to take with her onto the surface of the moon. If that scene had taken place on the Tardis it would have at least made sense. Hell if they had just established her to be an obsessive compulsive germaphobe it could have been lazily written off. Then they find the body of their crewmate in direct sunlight despite establishing that the creatures avoid it which did make sense at the time given that UV light kills bacteria. Later they are also crawling all over the surface in the light, so much for that idea then.
Then the creature itself. The premise of it having been inside the moon the entire time is completely ludicrous as such a thing would have been noticed. If the story had taken place around an alien planet yet to discover spaceflight then the idea would have been acceptable. When it hatches the surface of the moon just turns to harmless rubble instantly for whatever contrived reason the writers failed to think up. Anyone who has seen any kind of fish/insect/lizard/bird hatch knows full well that most of the shell remains intact. Trying to apply logic to the situation is fairly pointless though as it is also never made remotely clear where the extra mass the moon creature is acquiring is coming from. Had they said the creature was born with a wormhole in its stomach that was sucking in matter from elsewhere they at least could have tried to justify the idea. I sort of got bored of watching but it seemed to suggest it was the bacteria multiplying that caused the mass gain which still solves nothing as they could only have fed on the creature itself. At the end it simply flies off with what appear to be dragon wings. At least the star whale seemed to move via some as yet unknown propulsion method and not by simply flapping its wings in a vacuum...
The most ludicrous part of all however is naturally the end where the beast lays a 'new moon' egg which looks completely different to the moon and so screws with all past episodes that show it in the future. The earlier 'hologram' line was clearly devised to cover this but simply fails frankly. Worse of all though is the ridiculous idea of a newly hatched creature laying an egg larger than itself. The episode simply cuts to the new moon being in the sky and no one seems to question the sheer impossibility of this scenario.
The Waters of Mars storyline is also rendered seriously tenable after this one. As someone else pointed out this would mean that the human race put together a viable Mars colonisation programme in just a decade. It also means that after enduring major catastrophe on Earth they decided to spend fortunes flying to Mars instead of, you know, fixing stuff at home. The crew on the Mars mission are also dumbfounded as to how the Doctor arrived on the planet, which was a logical reaction at the time. Now though we have to assume that the astronaut who survived the mission and returned to Earth didn't bother telling anyone what had happened or how she got home. The only way anything that happened in this episode can possibly make sense is if the end of this series has some kind of major time reset event like that which occurred with the Master, or if it is revealed to all be a simulation or something.
All in all an episode which simply has to be completely ignored in order to continue enjoying the programme. What alarms me however is why this episode was ever put into production in the first place. They must have known at the time that it made absolutely no sense and didn't remotely fit in with other Doctor Who episodes. It concerns me now whether future episodes will ignore this one totally or try to justify the things that happened in it (like showing the new moon around Earth in future stories). Either way they must be really scraping the bottom of the barrel if this is the best writing they could find.