The answer is: a bit under 1400 kilometres in diameter, and no. But it’s a lovely exercise in googling and back-of-the-envelope calculations. First, let’s see how much water there is in oceans. The US ...

Here’s what you’ll learn when you read this story: Where Earth got most of its water is a subject of debate, but a new study suggests that the planet’s largest reservoir of hydrogen is not the ocean, ...