Oh, my God, oh, oh, wow, oh, oh, wow.

Oh, wow.

Oh, my.

Oh, my. Hi there, you're listening to The Science of Everything podcast, episode 22, our place in the cosmos.

In this episode, we're going to look at the location of the Earth in relation to, well, the cosmos, that is the wider universe.

So I'm going to start off with discussing the Earth and the Moon as a system and then move up through the solar system, nearby stars, the Milky Way galaxy, and right through to the universe in its entirety.

And each step of the way I'll be describing how the Earth fits into the hole and what structures we are embedded in and so on.

So you can get an idea of how the Earth fits into the big picture of things.

So, let's get into it,

and we'll start off by talking about the Earth and the Moon. The shape of the Earth is not

perfectly spherical. It is very close to that of an oblate spheroid, and an oblate

spheroid is basically a sphere that has been squashed from top to bottom. So if you can imagine, imagine an

orange, for example, and then put your hand on top of it and squash it down a little bit. So it's

fatter in the middle than it is from top to bottom, or in the case of the earth from pole to pole.

That is an oblate spheroid. So the earth's pretty close to a sphere, but it bulges a bit around the equator. The reason for that is because the Earth is rotating, and so as it rotates, it sort of flings the middle parts of the Earth

around the equator outwards a little bit, basically only to the angular momentum. That difference

is rather small, though. It's only about 43 kilometres. The Earth is only 43 kilometers longer

from one side to the other than it is

from pole to pole. And given that the diameter of the earth is about 13,000 kilometres,

43 kilometres is a rather small difference. Even Mount Everest, which is something like 8

kilometres tall, and the deepest crevice in the ocean, which is in the Pacific Ocean somewhere near Japan,

which is something like 10 or 11 kilometers deep.

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