Answer:
Build A Scale Moon and Earth Model
To understand how solar eclipses occur, we will build off of what we already know about the phases of the Moon. In essence, we will expand our model to think about how the Sun, Earth, and Moon are aligned in order for an eclipse to occur.eclipse model
A. Build a scale model of the Earth-Moon system using a piece of letter-sized piece of cardboard with two pins or nails inserted at opposite corners of the cardboard. (Insert the nails from the bottom, so that the sharp ends are pointed upward).
B. Place small balls of clay on top of the pins or nails to represent Earth and the Moon. The size of each piece of clay will be determined below.
Determine the scale of your system by determining the distance between the two pins or nails. Explain how you did this in words or with math. (The average distance between Earth and the Moon is 238,900 miles).
Using the scale for your model, make Earth and the Moon proportional sizes. Explain how you did this in words or with math. (Earth radius = 3,959 miles; Moon radius = 1,079 miles).
earth moon model
C. Connect Earth and the Moon with a taut piece of string. Ensure that the string remains attached right at the base of the clay. The cardboard will represent the orbital plane of Earth as it goes around the Sun, and the string will represent the orbital plane of the Moon as it goes around Earth.
D. Begin with the string parallel to the cardboard. Using a diffuse, bright light such as the Sun or a projector beam, place the model so that the Moon is closest to the light, and Earth is farthest away. The Sun, Earth, and Moon should be perfectly aligned so that they all fall in the same line. Observe the shadow that falls onto a piece of paper held vertically just beyond Earth.
Where does Earth’s shadow appear? What does it look like?
Where does the Moon’s shadow appear? What does it look like
Identify any similarities and differences between Earth’s and the Moon’s shadows.
Create a sketch below showing what this setup looks like from a side-view of the Sun, Earth, and Moon system. Include a sketch of how the shadows are produced and where they fall. Label each object.
Create a sketch below showing what this setup looks like from a top view of the Sun, Earth, and Moon system. Include a sketch of how the shadows are produced and where they fall. Label each object.
What is the phase of the Moon during a solar eclipse? Explain how you know
E. You might be aware that it is fairly rare to see a total solar eclipse. (Total solar eclipses can only be observed at the same location about every 375 years, with typically 2 total solar eclipses visible at some point on Earth each year). Elaborate on one or two possible reasons why you might not see total solar eclipses each month.
Model the Plane of the Ecliptic
eclipse plane
A. Push and pull on the nail representing the Moon, so that the string is no longer parallel to the cardboard. Orient the Moon so that its shadow appears to the left of Earth (when observing the shadows on a piece of paper, like in the diagrams below). Slowly rotate the system so that the Moon’s shadow moves toward the right. Observe how this changes the shadows produced on the paper. Draw the progression of the projected images seen on the paper for the following scenarios.
The Moon is “higher” than Earth. The Moon passes above Earth’s plane.
The Moon is “level” with Earth. The Moon passes along Earth’s plane.
The Moon is “lower” than Earth. The Moon passes below Earth’s plane.
B. Which of the above scenarios is a total solar eclipse? Explain your reasoning.
C. Consider the scenario you selected that represents a total solar eclipse. Notice, however, that the projected images you drew in all three cases above is not what is actually viewed by people during a total solar eclipse. Using your pen or pencil, place a dot on the surface of Earth and the Moon where they face one another.
Draw a sketch of what would be viewed from Earth when looking toward the Moon during a total solar eclipse.
Draw a sketch of what would be viewed from the Moon when looking toward Earth during a total solar eclipse. Try to represent this as accurately as possible.
In this exercise, you drew a sketch showing what would have been observed from the Moon when looking toward Earth. NASA has captured images of the shadow on Earth, called the Moon’s umbra, animated below:
eclipse shadow
Moon umbra during solar eclipse. Credit: NASA
One place that our cardboard and clay model of the Moon and Earth fails is in the size of the shadow on Earth.
