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 Penny Magnitudes

## Create piles of pennies to represent the magnitude values of stars

Use pennies and a calculator to show the value of each magnitude category for stars. Star magnitudes are represented by six traditional categories. Category six represents the dimmest stars one can see without using a telescope. Category one represents the brightest.

### Materials

• A calculator, either hand-held or on the computer
• Six paper dessert plates to model star magnitudes
• Four rolls (200) of pennies (or paper clips or nickels or stickers or crayon marks, etc.)
 Write magnitudes and calculator steps on each plate. Magnitudes Calculator Steps 6th 1 penny   = _________ penny 5th 1 x 2.51  = _________ pennies 4th 1 x 2.51 x 2.51 = _________ pennies 3rd 1 x 2.51 x 2.51 x 2.51 = _________ pennies 2nd 1 x 2.51 x 2.51 x 2.51 x 2.51 = _________ pennies 1st 1 x 2.51 x 2.51 x 2.51 x 2.51 x 2.51 = _________ pennies

Look at the plates of pennies.  Think about star magnitudes!

1. How many pennies are on the sixth magnitude plate? ________

2. How many pennies are on the first magnitude plate? ________

3. Which is dimmer, a fifth magnitude star or a second magnitude star? _________________________

4. Which is brighter, a second magnitude star or a third magnitude star? _________________________

5. How many times brighter is a first magnitude star than a sixth magnitude star? _______________

* Describe the magnitude scale for stars in your own words.

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* What new questions do you have about stars?

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** Try graphing your results. Place magnitude values on the X axis. Connect the plotting points with a curve. Put numbers by fives up the Y axis from 0 to 100.  Describe the slope of this curve.

01/16/2000

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