Havok wrote:For the record, the Doctor did not claim the moon was 100 million years old, but that the whatever it was, had been there for 100 million years. Or I guess, more accurately THIS moon had been there for 100 million years.
But the moon
has been there on the order of 100 million years. 5 billion years would have caused continuity problems the next time the Silurians turn up.
Basically it goes like this:
On the order of 100 million years ago, a giant egg was laid in the orbital path of earth and its twin planet mondas. This created a new planetoid, and the advanced civilization of lizard people living on earth detected it, coming towards earth. This caused them to panic, as they thought it would destroy the planet, so they went into hibernation underground (taking care not to accidentally turn themselves into werewolves and destroy the planet), or in a giant spaceship, set to return when the catastrophe is over. However, the egg was captured by the earth's gravitational field, and catastrophe never happened; so the lizard people continued staying in hibernation for millions of years. The existence of these lizard people (along with the werewolves and the planet mondas) was discovered in the 1980s, and they were named (rightly or wrongly) the silurians. The fact the moon is the egg, however, was not discovered for another ~60 years.