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# Video: Density in the Atmosphere of Neptune

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## Video Transcript

Hi, I'm Eylene Pirez, and I'm an astrophysicist, and this is "density in the atmosphere of Neptune." So, Neptune is one of the gas giants, and one of the things that we need to figure out when we're talking about pressures and densities is that they change a lot with height. So, depending in how deep it is in the planet, they change drastically. So, the thing to know, here, is how, what's the rate that it's changing? So, this is called the height's scale, and every 20 kilometers, that means if you travel 20 kilometers into Neptune, we drop, we, I mean, we increase by a factor of E. We use E as a terms of, as a mathematical term for, just 'cause it makes the math easier. E is about two point seven eight. So, the first thing to define is where is the surface of Neptune, and what's the density there? So, the surface of Neptune, we'll define it when the pressure is equal to one bar. We do the same with every single planet in the solar system, like in our ocean level. we also call that one bar. So, at one bar, what is the actual density? So, the density, here, is zero point four five kilograms per cubic meter. And, this decreases as we move out. So, here in the surface, we're at one bar, and when we have this atmosphere around us, it's decreasing until there's no longer an atmosphere, and it's decreasing at the rate of 20 kilometers. So, generally, the entire planet, the mean density, is 1,638 kilometers, kilograms per cubic meter. So, as you can tell, by the time that we get to the surface, the density has already dropped by a lot. So, the density at ground level for the atmosphere of Neptune is zero point four five kilograms per cubic meter. My name is Eylene Pirez, and I'm an astrophysicist, and this is "the density in the atmosphere of Neptune."