Hi guys i have been making this solor system simulator in python. I have added four planets and now I am trying to make it look a little nicer. What i am have trouble with is setting the background colour to be black (to give more spacey feel). But what ever I do doesnt seem to work. Can someone help? Also any suggestions that would improve the program are welcome.
Thanks

""" 
Python solar system

"""
from turtle import Shape, Turtle, mainloop, Vec2D as Vec 
from time import sleep

#Turtle.bgcolor("black")

G = 8

class Gravity(object):
    def __init__(self):
        self.planets = []
        self.time = 0
        self.distance = 0.1
    def init(self):
        for planet in self.planets:
            planet.init()
    def start(self):
        for i in range(500):
            self.time += self.distance
            for planet in self.planets:
                planet.step()

class Planet(Turtle):
    def __init__(self, mass, x_pos, velocity, gravity, shape):
        Turtle.__init__(self, shape=shape)
        self.penup()
        self.mass = mass
        self.setpos(x_pos)
        self.velocity = velocity
        gravity.planets.append(self)
        self.gravity = gravity
        self.resizemode("user")
        self.pendown()
    def init(self):
        distance = self.gravity.distance
        self.a = self.acc()
        self.velocity = self.velocity + 0.5 * distance * self.a
    def acc(self):
        a = Vec(0,0)
        for planet in self.gravity.planets:
            if planet != self:
                velocity = planet.pos()-self.pos()
                a += (G*planet.mass/abs(velocity)**3)*velocity
        return a
    def step(self):
        distance = self.gravity.distance
        self.setpos(self.pos() + distance * self.velocity)
        if self.gravity.planets.index(self) != 0:
            self.setheading(self.towards(self.gravity.planets[0]))
        self.a = self.acc()
        self.velocity = self.velocity + distance * self.a

## create compound yellow/blue turtleshape for planets

def main():
    s = Turtle()
    s.reset()
    s.getscreen().tracer(0,0)
    s.ht() #hide turtle
    s.pu() #pen up
    s.fd(6) # forward
    s.lt(90) #lt
    s.begin_poly() #begining of the polygon, the current position is the first vecto of the polygon
    s.circle(5) 
    s.end_poly() #end the polygon

    #creates m1, creats a semi circle  
    m1 = s.get_poly()
    s.begin_poly()
    s.circle(5)
    s.end_poly()

    #creates m2, uses the specs from the last recorded poly ^
    #m2 = s.get_poly()


    planetshape = Shape("compound")
    planetshape.addcomponent(m1,"green")
    s.getscreen().register_shape("planet", planetshape)
    s.getscreen().tracer(1,0)

    ## setup gravitational system
    gs = Gravity()
    sun = Planet(1000000, Vec(0,0), Vec(0,0), gs, "circle")
    sun.color("yellow")
    sun.shapesize(5)
    sun.pu()

    earth = Planet(12500, Vec(215,0), Vec(0,195), gs, "planet")
    earth.pencolor("green")
    earth.shapesize(2)

    moon = Planet(1, Vec(225,0), Vec(0,295),gs, 'planet')
    moon.pencolor('blue')
    moon.shapesize(1)

    mars = Planet(4000, Vec(0,327), Vec(150,0), gs, "planet")
    mars.pencolor('red')
    mars.shapesize(2)

    jupiter = Planet(750, Vec(-430,0), Vec(0,100), gs, "planet")
    jupiter.pencolor('purple')
    jupiter.shapesize(3)



 #   p5 = Planet (mass, x_pos, velocity, gravity, shape)
 #   p6 = (name, radius), mass, colour, distance, x velocity, y velocity

    gs.init()
    gs.start()
#   s.onclick(pause)
    return "Done!"

if __name__ == '__main__':
    msg = main()
    print(msg)
    mainloop()

The issue is that bgcolor() is a free function inside the turtle module, not a class method of Turtle. Try the following changes and you should be able to run it (is worked when I tried it):

from turtle import Shape, Turtle, mainloop, Vec2D as Vec, bgcolor
from time import sleep

bgcolor("black")

Thanks a million! wasnt too sure if i needed to import anything for the background still learning! thanks again

Python can help you ...

''' turtle_functions101.py
show the classes, functions/methods and constants of module turtle
'''

import turtle

# sort the items case insensitive
for item in sorted(dir(turtle), key=str.lower):
    print(item)

# optional
print('-'*30)
help(turtle.bgcolor)
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