1. Eclipses
and Tides
This powerpoint compiled by the Education Staff at the Lunar and Planetary Institute
Image from
Image from days after its final encounter with the Earth, the Galileo spacecraft looked back and captured this remarkable view of the Earth and Moon. The image was taken from a distance of about 6.2 million km (3.9 million miles). The picture was made with images taken through the violet, red, and 1.0-micron infrared filters. The Moon is in the foreground, moving from left to right. The brightly-colored Earth contrasts strongly with the Moon, which reflects only about one-third as much sunlight as the Earth. Contrast and color have been computer-enhanced for both objects to improve visibility. Antarctica is visible through clouds (bottom). The Moon's far side is seen; the shadowy indentation in the dawn terminator is the south pole Aitken Basin, one of the largest and oldest lunar impact features.

2. Intro
The Moon orbits at an angle with respect to the Earth’s orbit around the Sun.
We highly recommend doing Earth and Moon statistics with workshop participants before doing this powerpoint, if you intend to discuss the reason for phases or eclipses.
Ecliptic plane
Moon’s orbital plane

4. Eclipses Two kinds: Solar and Lunar
Only after phases have been mastered should you try to teach the reason for eclipses; otherwise, students will often assume that the reason for the Moon’s phases is the Earth’s shadow.
To understand why we have eclipses, we use the golfballs and blacklights, along with an embroidery hoop to model out the changing intersection of the Moon’s orbit with the ecliptic, as the Earth goes around the Sun.

5. Vocabulary
Umbra - is the innermost and darkest part of a shadow, where the light source is completely blocked. An observer in the umbra experiences a total eclipse. Penumbra -is the region in which only a portion of the light source is blocked. An observer in the penumbra experiences a partial eclipse.

6. Solar Eclipse When the Moon’s shadow covers part of Earth
Moon is in between Sun and Earth
When viewed from Earth, moon covers part or all of sun
Only happens at New Moon
Diagram from Fred Espenak, may be found along with lots of good information at

7. Total Solar Eclipse
Observers in the “umbra” shadow see a total eclipse (safe to view the Sun); can see the corona
Those in “penumbra” see a partial eclipse—not safe to look directly at Sun
Only lasts a few minutes
Path of Totality about 10,000 miles long, only 100 miles wide
Diagram by Fred Espenak and more information may be found at

8. Photo of a Total Eclipse
From

9. Eclipses
Lunar eclipse: A lunar eclipse occurs when the moon passes through the shadow of the earth.
Can be partial or full eclipse
Only after phases have been mastered should you try to teach the reason for eclipses; otherwise, students will often assume that the reason for the Moon’s phases is the Earth’s shadow.
To understand why we have eclipses, we use the golfballs and blacklights, along with an embroidery hoop to model out the changing intersection of the Moon’s orbit with the ecliptic, as the Earth goes around the Sun.

10. When the Earth’s shadow covers the Moon, we have a lunar eclipse
Additional details are at
When the Earth’s shadow covers the Moon, we have a lunar eclipse

11. Why is the Moon red during an eclipse?
The Earth’s atmosphere filters some sunlight and allows it to reach the Moon’s surface
The blue light is removed—scattered down to make a blue sky over those in daytime
Remaining light is red or orange
Some of this remaining light is bent or refracted so that a small fraction of it reaches the Moon
Exact appearance depends on dust and clouds in the Earth’s atmosphere