Sun-Earth-Moon Relationships

Journey into SpaceJourney Museum, July 18-20, 2012

Modified fromModified fromRick Varner, AESPRick Varner, AESP

Goddard Space Flight CenterGoddard Space Flight CenterGreenbelt, MDGreenbelt, MD

Aristarchus of Samos

Early Scientists’ Work

How Far Away is the Moon?

~ 384,000 km

Too Far Away For a Ruler!Too Far Away For a Ruler!

Average Distance 384,400 km (~240,000 mi)

Let’s use a distance that we already know to develop our model!

384,000 km

Earth’s diameter = 12,756 km (rounded 13,000 km)

Moon’s diameter = 3,475 km (slightly more than ¼ the of Earth)

13,000 km=30 (29.54)

Mathematics

Mathematics

~13,000 km~13,000 km

The Moon is approximately one fourth the diameter of the Earth. 1” and ¼” craft beads can be used to

simulate the Earth & Moon.

Clipped to a yard stick 30” apart creates a mobile model that can used for both distance

and eclipse simulations. Since this is a rounded measurement, the actual distance is from

bead surface to bead surface.

The Model

Earth to Moon Scale Modeling Variations:

Age/Developmentally Appropriate Audiences

Pre-existing Models: Replogle Small Lunar Globe

12” Earth Globe

Athletic Balls: Basket Ball & Tennis/Baseball Ball

Painting, Drawing, Clay, Play-Dough, etc…

Balloons: Blue Round - Earth

White Round - Moon, Red Balloon?

Mathematical Models: using only numerical measurements

Diameter Approximate Scale Models

Earth Moon

12,756 km 3,476 km

~24 cm 6.9 cm

The Phases of the Moon

Moon Phase Modeling• Ping Pong Ball• Hot Glue• Long Golf TeeGlue the ping pong ball to the golf tee with the

company logo covered by the top of the golf tee.If the moon is visible, hold the ball at arm’s length

below the moon and compare.Rotate counterclockwise to simulate lunar phases

Protect eyes from direct viewing of the sunProtect eyes from direct viewing of the sun.

Ping Pong Ball Lunar Model

12 p.m. Noon

12 a.m Midnight

6 a.m.9 a.m.

6 p.m.

9 p.m.

3 a.m.

3 p.m.

The Sun is VERY far

away!

1

1

2

2 3

34

4 5

5

6

6 7

7

8

8

Plate Activity

6/2/1211:49pm

95%

6/8/124:48am

77%6/16/1210:49am

8%

6/4/1212:52am

6/11/126:42am

50%

6/19/1211:03am

6/20/122:04pm

1%

http://aa.usno.navy.mil/data/docs/RS_OneDay.php

Antonio Cidadao: http://www.usno.navy.mil/USNO/astronomical-applications/images_aa/Moon_movie.gif

EclipsesThe Model

1. Use the sidewalk or a flat surface to align the shadows.

2. Look at the shadows on the background, then look at the beads.

Sun • Moon • Earth = Solar EclipseSun • Earth • Moon = Lunar Eclipse

SolarSolar Eclipse viewed from Mir Eclipse viewed from Mir http://apod.nasa.gov/apod/ap990830.htmlhttp://apod.nasa.gov/apod/ap990830.html

August 11, 1999

May 20, 2012 Terra SpacecraftMay 20, 2012 Terra Spacecraft

December 20, 2010Lunar Eclipse

Connecting the Lunar Phases to the Solar & Lunar Eclipse

Sky & Telescope Article on 2010 Eclipses:http://www.skyandtelescope.com/observing/objects/eclipses/80386602.html

http://www.mreclipse.com/Special/SEprimer.html

http://www.mreclipse.com/Special/SEprimer.html

Aug 21, 2017Next total solar eclipse…visible in the U.S. from SC to OR