How Far is the Moon?

Most of us have difficulty imagining the size of the solar system.  Just looking at the numbers is often not enough.

A good example of this is the distance to the moon.

An encyclopedia tells us that the average distance to the moon is 384 000 km.  But how far is that?

Take a globe.

If we took the moon and reduced it to scale how far away  should the moon be from this globe?

Ask a few students to stand where they think the moon should be placed.

When asked to hold a small ball (the moon) its correct distance from the globe students usually hold it about a meter away

With a class, I would assign the following homework:

We list on the board ways to get information.

Books, computer, TV. Library

We discuss this list and I add relatives and classmates.

They are then asked to  check in an encyclopedia, library,  the internet  or call a classmate or relative for these two facts.

1.  What is the circumference of the Earth?  The length of the equator.

2. What is the average distance to the moon?

In Nova Scotia ... Kilometers please.

The next day we recorded the results on the Board.

We usually agree that the length of the Equator is 40 000 km.

The average distance to the moon is about 384 000 km.  (we might talk about apogee and perigee at a later time.)

Then I would pass out paper and calculators and ask them to form groups and  calculate how many trips around the Equator would equal a trip to the moon.  They were asked to show their calculations and to make sure to  show the answer in a statement.

After the groups had time to present their findings  I would take our globe and some yarn.

Since we found that a trip to the moon is equal to 9.5 trips around the Equator we would wrap the yarn around the Equator and then cut it and unwind it.

We were always surprised that the moon's orbit would not fit inside the classroom and we would have to go outside or to the gym to unwind the yarn.

Evaluation : I  used a 6 point rubric for the groups.

Completes Presentation

Shows problem

Solves problem correctly

Makes correct statement.

Shows evidence of cooperative work.

Follow up:   Display work.   If possible schedule Interview  with groups that have problems.  ex. " A trip around the equator is the same as going 9.5 times around the moon."

Examples of Group Work

October 2009  Petite Elementary

Devan. & Johua's Solution

40 000 + 40 000 + 40 000 + 40 000 + 40 000 + 40 000 +40 000 + 40 000 + 40 000 + 20 000 = 380 000

9 x 40 000 + 20 000 = 9 1/2 times

A trip to the moon = 9 1/2 times around the Earth

October 2009 Petite Elementary

Shelby Kaitlyn and Bubbles

40 000 x 1 = 40 000

40 000 x 2 = 80 000

40 000 x 3 =120 000

40 000 x 4 = 160 000

40 000 x 5 = 200 000

40 000 x 6 = 240 000

40 000 x 7 = 280 000

40 000 x 8 = 320 000

40 000 x 9 = 360 000

9 1/2 = 360 000 + 20 000

Extra:  A trip to the sun = 390 trips to the moon so how many times would we have to wrap our yarn around the equator to equal a trip to the sun?

Want to find out more about the Moon?  Check out our  Moon page.

Web Sites

Ellipse (6)

on the size of the Solar System.

Nine Planets info on the moon

Our Moon Page

Virtual Reality Moon Phase pictures

The Moon   Starchild  NASA

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