The first picture is a dark image of a planet with a sligthly threatening atmosphere. It looks like the upper half of a mushroom cloud, but it could be also seen as the earth violently torn apart. This is why I think , given the context, that it symbolises the threat of a nuclear war, and more universally, the threat of a dystopia.

The last picture shows a beatiful utopia. I thought it's there to give a message of the type: "If everything goes well, we can still achieve a very good future." That is, while the first picture symbolises the threat of a dystopia, the last one symbolises the hope and possibility of an utopia.

Of course, this is merely my interpretation. There are very many ways one can inerprent these pictures.