8 June

This is how the Earth got its tilt. Early in its history something about the size of Mars crashed into us, breaking off a huge amount of rock and rubble. That rubble and gravity together then formed the moon, and the collision tipped the Earth off its axis. The moon today keeps that tilt in place. That tilt is probably the reason we're here. Without it there would be no seasons. Without seasons it's likely the climate would be in bands that get progressively colder as you moved from the equator towards the poles, and winter would be permanent there. The only habitable bit would be around that equator, but it would have continuous rainfall and leach any nutrients from the soil, making it almost impossible to grow any food. This climate would also be perfect for disease organisms, even worse than the tropics today. Just because I think this stuff is bloody interesting.