Q:

Creating multiple colored turtles in one window in editor on Python 3.4

So far I have this and it makes two circles but one is off-screen. I want to center it and have them separate from each other. Right now it does two loops but I want it to do one small circle then go on to make a larger one around the first in the middle of the screen. Both need to be diff. colors.
def sun_and_earth():   
    import turtle  #allows me to use the turtles library
    turtle.Turtle()
    turtle.Screen()  #creates turtle screen
    turtle.window_height()
    turtle.window_width()
    turtle.bgcolor('grey')  #makes background color
    turtle.color("red", "green")
    turtle.circle(2, 360)  #draws a (size, radius) circle
    turtle.circle(218, 360)
    turtle.exitonclick()  #exits out of turtle window on click of window

A:

I think you may have some misunderstanding with regard to some of the functions in the turtle library. Firstly, turtle.window_height() and turtle.window_width() return the height and width of the window, so (as these values are not being assigned) those two lines do nothing. Similarly, turtle.Screen() returns an object, so again that line does nothing.
In order to centre your circles, you need to change where the turtle starts by using the turtle.setpos() function. This will change the x and y coordinates of where your turtle is. If you start the turtle one radius down, this will effectively centre the circle at (0, 0), because the center of the circle is (from the documentation) one radius to the left.
Remember to take your pen off the page when you are moving so that you don't draw lines between the two points by accident, and to put the pen back down again when you want to draw again.
Try this code:
import turtle
turtle.Turtle()
turtle.bgcolor('grey')

# decide what your small circle will look like
smallColour = "red"
smallRadius = 5

# draw the small circle
turtle.color(smallColour)
turtle.penup()
turtle.setpos(0, -smallRadius)
turtle.pendown()
turtle.circle(smallRadius)

# decide what your large circle will look like
largeColour = "white"
largeRadius = 100

# draw the large circle
turtle.color(largeColour)
turtle.penup()
print(turtle.pos())
turtle.setpos(0, -largeRadius)
print(turtle.pos())
turtle.pendown()
turtle.circle(largeRadius)

turtle.penup()
turtle.setpos(0, 0)

I hope this helps, but I think that you have a few misunderstandings about the use of the turtle, it might be a good idea to look at a tutorial or maybe take a look at the documentation
Best of luck

