How the Sun and Moon Can Appear to be the Same Size

Shuttle

The diameter of the Sun is over 400 times the diameter of the Moon. So how can they appear to be the same size? Try this experiment! You need three people for this activity.

Materials Needed:

1.Have one person hold out the large ball, which will represent the Sun. Hold it out away from your body so that your hands are on the top and bottom of the ball.

2.Have another person hold up the small ball (representing the Moon) directly in front of the "Sun". Stand about 6 feet away and hold the ball out in the same way the person is holding the "Sun".

3. The third person should stand in front of the person holding the "Moon", looking toward the person holding the "Sun". This person will represent what someone on Earth would see. Have the Sun and Moon adjust themselves so that they appear to be in a straight line, with the Moon between the Earth and Sun.

4.The person holding the Sun should begin moving away from the person holding the Moon (again keeping the Earth, Moon, and Sun in a straight line) until the Sun and the Moon appear to be the same size to the person representing the Earth.

Measure and record the diameters of the Sun and Moon.

Measure and record the distances from the Earth to the Moon and the Sun when they appear to be the same size.

Shuttle

The StarChild site is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA/ GSFC.

StarChild Authors: The StarChild Team
StarChild Graphics & Music: Acknowledgments
StarChild Project Leader: Dr. Laura A. Whitlock
Curator:Meredith Gibb
Responsible NASA Official: Phil Newman
If you have comments or questions about the StarChild site, please send them to us.