 Greetings and welcome to the Introduction to Astronomy. In this video we are going to look at the Planetary Orbit's Lab and talk a little bit about that and we will help us look at a few things in terms of Kepler's and Newton's laws of motion. So it'll give us a little bit better understanding of those and you will of course want to look at the main content here for part of your part of your lab work and then we will use the Planetary Orbit Simulator to do the remainder and that's what we're going to take a look at here is how that works. So as we go into the Planetary Orbit Simulator what we find is we will have as we usually do a number of windows here first of all we can see the orbit itself in the large window here this has a number of different tabs that can look at the different laws Kepler gave us and that of Newton and then there is some information here so that we can change the orbit we can set it to a specific planet or we can adjust it manually using a specific semi-major axis and eccentricity and then of course we can start the animation and change the animation speed how many years will pass for every second and there's a couple of other options that you can use here so just to look at a couple of examples of what you can see here if you look at Kepler's first law it'll tell you about the types of orbits that the orbits are ellipses and if you want to see where all the other pieces are there's a bunch of checkboxes here that will show the empty focus the center of the ellipse and the major and minor axes and then if you want to see what the values are it will tell you the various things here and you can adjust it so if we're looking at Mercury we see that however if we want to look at Jupiter it will actually change the settings and it will scan in so that you can now see where everything is for Jupiter's orbit and we can see that the values change for Mercury had a much higher eccentricity and the orbit looked far more elliptical Jupiter's orbit is much closer to being a circle now we're also going to look at the other laws so we can look for example Kepler's second law and that will give you a chance let's clear those to look at how the orbit how the speed of the orbit changes so let's go back and look at Mercury again so as we go ahead and set this for Mercury and go ahead and look at Mercury's orbit and if we want to look at Kepler's law for example Kepler's second law we can do the sweep continuously and then let it start sweeping and that will go through really quickly and let's go ahead and pause that and it will show that we have different size sectors for each of these each of these times is equal so this time is the same as this time and what it's really showing us is that the planet is moving faster here close to perihelion and slower here at apelion when it is further away from the sun so we can adjust the controls and you'll follow the instructions there to see what you can learn about Kepler's second law we also want to clear this and let's take a look at Kepler's third law briefly Kepler's third law says that the square of the period of a planet orbiting the sun is equal to the cube of its semi-major axis and it does the calculation here for the selected planet in this case we're still looking at mercury and we find that a cubed and p squared are actually equal and give us the same value and that's what we will see for all of the planets and what it really tells us is the further a planet is away from the sun the slower it is going to be moving the longer the time it will take and this gives us the relationship between those two so you'll look at kepler's third law there and then finally you can look at the newtonian features and let's go ahead and clear that and newtonian features will look at it in a little more physical sense in kepler's laws kepler's laws are very specific to the solar system and even more specific to items orbiting the sun now we'll be able to see a little more detail and be able to see this from the newtonian view in that we can see the velocity and the acceleration things we don't look at at in kepler and the angle between them and we'll be able to understand how that can affect things and if you want to turn those on when you're running you can turn on the vector so you can see the velocity in the purple and the acceleration in the red which direction those are pointing and as you run the animation here going very quickly let's slow that down a little bit so you can see it better and you can watch how the direction and the size of those arrows change the acceleration arrow changes a little bit getting less when you get further away from the sun and larger when you get further closer but it is always pointing towards the sun the velocity arrow is constantly changing direction meaning that this object is constantly accelerating and remember that an acceleration can mean a change in velocity itself or can actually mean a change in can just be a change in direction so we can look at those various angles and try to better understand what is happening here so using the newtonian one will give you a little bit better idea on that so you'll be able to look at all three of these are four of these simulations as part of the lab that you will do you'll look at all all of these and it will tell you what adjustments to make for the orbit settings if you need to adjust the animation you can change the speed and any other options that you want to be able to see there and it will tell you make sure you're following through the settings there as you work through the lab so that concludes this lecture on the planetary orbit simulator we'll be back again next time to look at another one of these simulations so until then have a great day everyone and i will see you in class