Astronomy Lesson Plan: How Big is the Solar System?


Astronomy, like the size of the solar system, is such a vast subject that it can be a challenging one to teach. It’s a fascinating topic and there are so many angles to choose when trying to effectively teach astronomy.

Our experience is that most public schools teach astronomy in a way that does not inspire awe and elicit the interest the topic warrants. Most astronomy courses are not interactive and this is definitely a topic that needs to be hands-on. Powerpoints and lectures won’t cut it.

So we created a lesson plan drawn from The Thousand Yard Model or The Earth as a Peppercorn created by Guy Ottewell.

This lesson gets kids outside and keeps them energized and engaged. The goal is to teach the size and scale of the universe in a way that is realistic – a challenging endeavor given the enormity of the topic!

Lesson Plan Title: How Big is the Solar System?

Concept / Topic To Teach: An understanding of the scale of the universe by teaching the relative size and spacing of the planets.

Goal: To help students obtain a clear understanding of the size of the sun and the other planets in our solar system. Help students grasp the concept of the vastness of our universe.

Age Range: This lesson plan applies to a vast age range – ages 6-18. The basic activity remains the same for all ages. The teacher’s discussion questions will vary greatly according to the audience. This particular lesson plan applies to ages 6-10.

Specific Objectives:

  • Engaging students to be excited and in awe of the huge world we live in!
  • Teaching basic concepts of measurement and distance (inches, yards, miles)
  • Strengthening knowledge of planets in the solar system
  • Increasing understanding of size of the sun and other planets
  • Learning the scale of the solar system
  • Encouraging children to explore the universe on their own (e.g., get a telescope for backyard viewing)


  • Sun – any ball, diameter 8.00 inches (a bowling ball is this size but that is too heavy, try an inflatable ball)
  • Mercury -a pinhead, diameter 0.03 inch
  • Venus – a peppercorn, diameter 0.08 inch
  • Earth- a second peppercorn
  • Mars -a second pinhead
  • Jupiter – a chestnut or a pecan, diameter 0.90 inch
  • Saturn – a hazelnut or an acorn, diameter 0.70 inch
  • Uranus – a peanut or coffeebean, diameter 0.30 inch
  • Neptune a second peanut or coffeebean
  • Pluto – a third pinhead (or smaller, since Pluto is the smallest planet)
  • Pieces of paper or cards to pin/place planets on
  • Label each piece of paper with the name of the planets
  • The pinheads will need to be pinned to labeled cards or paper to make them visible.
  • A megaphone (not essential, but helpful)
  • Find space near the school (playground/field) where you can walk one thousand yards (preferably in a straight line). It is not imperative that it be in a straight line if that is not possible. This may be tough to find.

Anticipatory Set (Lead-In):

Here are some questions to start the conversation:

  • Does anyone know what makes up our solar system?
  • Who can tell me what is the biggest planet?
  • Does anyone know how far it is from the Sun to the Earth?
  • Who knows something really interesting about the solar system that you want to share with the class?

Teacher’s Explanation:

  • The solar system really is too big for us to imagine. It is more than 9,000,500 miles.
  • From the Sun to the Earth is about 93,000,000 (93 million) miles.
  • The average distance from the Sun to Pluto is much larger, about 40 times the distance from the Sun to the Earth.
  • The Sun to Pluto distance is typically referred to as 3.7 BILLION. To give you a sense for how far this is, imagine you are driving to Pluto on the highway at the speed of 60 miles per hour, it is going take you about 7 thousand years to reach your destination!
  • Planets are so small and the distances between them are unbelievably large.
  • In order to understand the size of the planets and the distances between them, we’re going to go outside in a few minutes and imagine ourselves as the sun and planets. Before we do that, lets review a few things.

Step-By-Step Procedures:

  1. Put the objects out on a table and place them in a row. Explain to the class that these objects will be used to create your class model of the solar system.
  2. Now is a good time to review the number of planets -9- and their order.
  3. You have probably already taught a mnemonic like “My very easy method just speeds up names” or “My very educated mother just served us nine.”
  4. Ask the class “How much space do we need to make the solar system?” Children may think that spacing out the objects on the table is enough.
  5. Now is the time to introduce the concept of scale.
  6. Explain to the class – “This peppercorn is the Earth we live on.”
  7. Ask the class “Does anyone know how wide the Earth is?” The Earth is eight thousand miles wide! The peppercorn is eight hundredths of an inch wide.
  8. Ask the class “Does anyone know how wide the Sun is?” It is eight hundred thousand miles wide. This ball representing the sun is only eight inches wide. Explain that one inch in the model represents a hundred thousand miles in reality.
  9. Explain to the class that one yard (36 inches/3 feet) represents 3,600,000 miles. Take a pace (one big step) and explain to the class that this distance in your scale of the universe model represents “three million six hundred thousand miles.”

Mnemonic Refresher

MyM = Mercury
VeryV = Venus
EasyE = Earth
MethodM = Mars
JustJ = Jupiter
SpeedsS = Saturn
UpU = Uranus
NamesN = Neptune

10.  This is a good time to review the scale and measurements. It may be helpful to create a handout of the scale or simply put this up on the chalkboard.

Real In model

 RealIn Model
Earth’s width8,000 miles8 / 100 inch
Sun’s width800,000 miles8 inches
Therefore scale is100,000 miles1 inch
Therefore3,6000,000 miles36 inches / 1 yard
And Sun-Earth distance93,000,000 miles26 yards

11.  Ask the class, “Who remembers what the distance is between the Earth and the Sun?” In our model it will be 26 yards.

12.  Ask a student to start at one side of the room and take 26 paces. S/he comes up against the opposite wall at about 15 paces. This should help the class begin to grasp the concept of scale.

13.  Tell the class it’s time to create your solar system outside as there is clearly not enough room inside. Get the class energized and enthused by telling them its time to take a space journey. Lets stretch our legs and build our solar system!

14.  Before you leave, distribute the Sun, the planets, and the labeled paper to members of the class. Make sure that each student knows the name of the object he or she is carrying. As this model calls for participation from eleven students, you’ll want to pair up students and assign a planet to more than one child.

15.  Take the class to a pre-determined point where you can walk a thousand yards (preferably in a straight line) from one end to another. This may not be easy. A straight line is not essential and you don’t have to see from one end of it to the other. You may have to circle back. It may be more memorable if you label the thousand yards such as, “from the playground to the back parking lot.”

16.  Put the Sun ball down, and march away from it as follows. (After the first few planets, ask a student to be responsible for the pacing so you are free to talk and move around. Give this person a special name like “Pace Craft” or “Pace Explorer.”

17.   Take 10 paces. Call out “Mercury, where are you?” and have the Mercury person put down his/her card and pinhead.

18.  Take another 9 paces. Ask Venus to put down her peppercorn. At this point you may want to take out the megaphone so everyone can hear you. This is not essential but it may place less strain on your vocal chords.

19. Take another 7 paces. It’s Earth’s turn.

20.  Ask the class if they notice anything amazing so far? Point out that Mercury is so close to the sun but we never see it (except sometimes in the Sun’s glare at dawn or dusk). It is like a scorched rock and it is lost in space. And as for the distance between Earth and the Sun, can you believe that it warms us so well and we are so far from it?

21. Take another 14 paces. Mars.

22. Take 95 paces from there to Jupiter.

23.  As you or the Pace Explorer is taking paces, continually ask the class questions such as “Who knows an interesting fact about Jupiter?” What is so amazing about this? Point out that Jupiter is so large that you could fit all the other planets inside it. And in our model it is just a chestnut, more than a city block from its nearest neighbor in space!

24.  Another 112 paces. Saturn

25.  Another 249 paces. Uranus

26.  Another 281 paces. Neptune

27. Another 242 paces. Pluto

28.  At this point, the Pace Explorer has marched more than half a mile! The distance in the model adds up to 1,019 paces. A mile is 1,760 yards.

29.  Ask the class again “What observations they have about the model? Point out that the sun ball is no longer visible even with binoculars from the pinhead Pluto. The inconceivable size and wonder of space may now start to set in.


An interactive exploration of the size of the solar system like this, may make your students eager for more. One way to keep up the momentum is to repeat the activity and vary it a bit. Perhaps ask student pairs to write up fun facts on their planet cards about the planet they represent. Have them share their facts and see who can guess which planet they are.  Or you can do the walk once more from the Sun to Pluto and them immediately in reverse, starting with Pluto. This will help reinforce the concept of the scale of the solar system through repetition.

Maintain their interest and enthusiasm by encouraging students to get binoculars and explore the universe at night. There are specific dates and times of the year when certain planets come into view. Sky and, and the Astronomy Calendar of Celestial Events 2010 are resources that provide these details, as well as much more interesting information about astronomy.

We aim to provide lesson plans on conventional topics that are anything but conventional. Our goal is to make the learning effective, fun and inspiring. If you have any suggestions for this lesson plan, we’d love to hear from you. And if you are interested in us creating innovative lesson plans on other topics, we want to hear from you!