Orbits Part 1 - Astronomy at West - Solar System 3E1
Astronomy
Let us talk about The Solar System
Mass, density, gravity, and escape velocity. When we're first starting to talk about orbits, orbits really are the most apparent around the sun. That is because all the planets are orbiting mostly of just above or below the ecliptic extending outward from the sun's equator. And we view this from earth as if you are viewing the solar system from the northern hemisphere the North Pole. And there are two different things that are really going to impact gravity. So we are looking at something that is going to lead to gravity, what is going to make an object interact in the sun's gravity well more than it would for a different object. And this is not size. This is an interaction of mass, so mass is the amount of matter in an object, so the amount of matter in an object versus how dense the object is. So the matter density. And object with a lower density is not going to have as much gravity as an object that is of higher density. And we'll interact differently in its orbit based on its size.
Now the inner planets, the inner planets, are very dense. They're dense. So all of the matter in them is clumped together. Very sparsely. That means that on their surfaces, they have a lot more if you were standing on the surface, you'd be closer to the center of mass in that object. And so you would be affected by the gravity more because of how close you are to that center of mass. And so on the sun's gravity wells spectrum, if this is the sun's gravity well going way down there, you have these little dips. Corresponding to where the interior planets are deforming that gravity well in the fabric of space and time. And so that is what the gravity is doing. Now for the outer planets, the same things happening, except for there's a big difference in the outer planets density. The outer planets tend to be very sparse in their density because they're mostly made of light gases. This does not mean that they have a lower gravity. It just means it's just they are less dense.
If I were to look at their surface, their surface gravity is not pulling down as forcefully as it is on earth because they are less dense. But because they are so much more massive, the more massiveness of how much masses they are and that sounded kind of like a limerick. The more massive, massive, massive they are. The more massive, so they're going to have a higher gravity than earth. But they are much, much less dense. Less stacks. So as density and mass come together, depending on how much mass you have in a general area. And if you have it close to the other, this can affect what is called the escape velocity of the planet. And we're going to change that diagram. We're going to say no, we're going to use a circle. So if I have a planet and I want to escape from that planet, I need to have some sort of velocity just like the Newton thought problem of a cannon, I have to add some velocity that escapes and continues to orbit around that planet. And so an escape velocity. Is directly related to the mass of the planet.
So the mass of the planet is giving the planet that gravity is a mass leading to the gravity, but it also has to do with the planet's density. Because if I have a more dense planet, you will be closer to the object center of mass. And so you will be closer to the gravity that you are trying to escape from. So an object that is less dense may actually have an escape velocity, less than that of another object that might have more mass, depending on how far you are from the center of mass because that's how gravity works. Thank you for watching. This has been Justin Higgins. I have a glorious day and B excellent to each other.