types knew what the mass of the world was, i say, including the mud puddles they don't know about in ceylon? including the sticks and stones and the elephants they don't know about up in india? including all the lava that they don't have a good handle on way down underneath and what's at the center of the world, they know what that is too? how do they know such thing? they'd be knowing such thing, honey, because...one left and that's the mass of the world. ain't that neat? next time, we're gonna be talking about ocean tides. and we'll be talking about ocean tides, we're gonna be talking about the role that the moon plays when it pulls on the oceans of the earth, okay? but let's talk a couple of things about the moon now. you probably all know that there's only one side of the moon that can be seen from the planet earth, yeah? you look up and there's one face looking at you all the time, alright? now why is it that one face is looking at us all the time? some people will say, well, the fact that one face is always looking at us and it wasn't until the astronaut types went out and looked at t