Star Pattern in Python Turtle

Intermediate · Patterns and spirals · 37 lines · draws in about 12 seconds

Every star is drawn around the same centre, a little smaller and turned 5 degrees more than the one before, so together they swirl inward.

Star Pattern in Python Turtle: the finished drawing

import turtle

screen = turtle.Screen()

screen.bgcolor("black")

screen.title("Star pattern")

t = turtle.Turtle()

t.speed(10)

t.pensize(2)

colors = ["red", "orange", "yellow", "lime", "deepskyblue", "violet"]

def draw_star(radius, angle):

# A star around (0, -20), with its top point turned by angle.

# (0, -20) is a little low because a star reaches higher above its centre than below.

t.penup()

t.goto(0, -20)

t.setheading(90 + angle)

t.forward(radius) # out to the top point

t.right(162) # face along the first line

t.pendown()

# Each line is 1.902 times as long as the distance from the centre to a point

for i in range(5):

t.forward(radius * 1.902)

t.right(144)

# 20 stars, each one smaller and turned a little further

radius = 220

for i in range(20):

t.pencolor(colors[i % 6])

draw_star(radius, i * 5)

radius = radius * 0.9

t.hideturtle()

turtle.done()

Open in the editor

How the code works

A star around a centre

The turtle goes to the centre, faces 90 + angle and moves out to the top point, where right(162) faces it along the first line. Each line of a five-pointed star is 1.902 times as long as its radius, and a right(144) after each of the five lines brings the turtle back to the top.

def draw_star(radius, angle):
    # A star around (0, -20), with its top point turned by angle.
    # (0, -20) is a little low because a star reaches higher above its centre than below.
    t.penup()
    t.goto(0, -20)
    t.setheading(90 + angle)
    t.forward(radius)          # out to the top point
    t.right(162)               # face along the first line
    t.pendown()
    # Each line is 1.902 times as long as the distance from the centre to a point
    for i in range(5):
        t.forward(radius * 1.902)
        t.right(144)

Smaller and turned

i * 5 turns each star 5 degrees more than the last, and colors[i % 6] gives it the next colour. radius = radius * 0.9 makes the next star 90 percent of the size, so the stars shrink toward the middle.

# 20 stars, each one smaller and turned a little further
radius = 220
for i in range(20):
    t.pencolor(colors[i % 6])
    draw_star(radius, i * 5)
    radius = radius * 0.9

Make it yours

Change the code above and press Run. Some ideas:

Change i * 5 to i * 12 for a looser swirl.
Change 0.9 to 0.95 and range(20) to range(40) for more stars packed closer together.
Change colors[i % 6] to colors[i % 2] so the stars alternate red and orange.

What it uses

Every turtle command the site supports is listed on Python turtle online.