Lunar Eclipse

Lunar Eclipse

Middle School

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Learning Objectives

• Define a lunar eclipse and the specific alignment of the Sun, Earth, and Moon.

• Describe Earth's umbra and penumbra and the three resulting types of lunar eclipses.

• Explain why lunar eclipses are longer and more visible than solar eclipses.

• Understand why a lunar eclipse does not happen during every full moon.

Key Vocabulary

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Lunar Eclipse

A celestial event where the full Moon passes directly through the Earth's shadow.

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Umbra

The darkest, central part of a shadow, where the light source is completely blocked.

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Penumbra

The lighter, outer part of a shadow, where the light source is only partially blocked.

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Total Lunar Eclipse

This happens when the entire Moon passes completely into Earth's dark umbral shadow.

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Partial Lunar Eclipse

This type of eclipse happens when only a portion of the Moon enters Earth's umbra.

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What is a Lunar Eclipse?

• Earth passes directly between the sun and the full Moon.

• ​This alignment causes Earth to cast its shadow on the Moon.

• As a result, the Moon's surface is temporarily dimmed.

• This event is visible from the night side of Earth.

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Multiple Choice

Under which two conditions does a lunar eclipse occur?

• During any moon phase, when the Earth casts a shadow.

• During a first quarter moon, when the Earth is between the sun and Moon.

• During a full moon, when the Earth is between the sun and Moon.

• During a new moon, when the Moon is between the sun and Earth.

Earth's Shadow & Types of Eclipses

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Total Lunar Eclipse

• ​The umbra is the inner, darkest part of Earth's shadow.

• ​​Sunlight is completely blocked when the Moon passes through the umbra.

• ​During this, the Moon often takes on a dull red glow.

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Penumbral Lunar Eclipse

• ​The penumbra is the outer, fainter part of Earth's shadow.

• ​​Sunlight is only partially blocked when the Moon is in it.

• ​It causes a subtle dimming that can be hard to see.

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Partial Lunar Eclipse

• ​This happens when the alignment of Earth and Moon is imperfect.

• ​​Only a portion of the Moon passes through the dark umbra.

• ​The rest of the Moon remains in the fainter penumbra.

Multiple Choice

What type of eclipse occurs when the entire Moon travels into the part of Earth's shadow where light is completely blocked?

• A partial lunar eclipse

• A solar eclipse

• A penumbral lunar eclipse

• A total lunar eclipse

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Duration, Visibility, and Frequency

Duration & Visibility

• ​Because Earth's shadow is so large, a lunar eclipse can last for several hours.

• ​​They are visible over a very large area of the Earth, unlike solar eclipses.

• ​This makes it much more likely for any person on Earth to see one.

Frequency

• ​Partial lunar eclipses are common, happening at least two times every single year.

• ​​However, a lunar eclipse does not occur every month when there is a full moon.

• ​The Moon's orbit is tilted by 5 degrees relative to Earth’s orbital plane.

Multiple Choice

Why are lunar eclipses more commonly seen than solar eclipses?

• Because the Moon's orbit has no incline.

• Because Earth's shadow is large, and the eclipse covers a wide area.

• Because they happen every single month.

• Because they are much brighter than solar eclipses.

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Common Misconceptions About Lunar Eclipses

Misconception	Correction
A lunar eclipse happens every full moon.	The Moon's orbit is tilted, so it usually misses Earth's shadow.
The Moon is invisible during a total lunar eclipse.	The Moon appears reddish due to sunlight refracted by Earth's atmosphere.
It is dangerous to look at a lunar eclipse.	Lunar eclipses are safe to view. Solar eclipses require eye protection.

Multiple Choice

What is the primary reason a lunar eclipse does not occur every month during a full moon?

• The Earth's shadow is too small.

• The Moon's orbit has a 5-degree incline.

• The sun is not bright enough.

• The Moon moves too quickly.

Multiple Choice

Which statement accurately contrasts the umbra and penumbra?

• The umbra is where light is completely blocked, while the penumbra is where it is partially blocked.

• The umbra is larger than the penumbra.

• The penumbra is the darkest part of the shadow, while the umbra is the lightest part.

• Only total eclipses involve an umbra; partial eclipses only have a penumbra.

Multiple Choice

If the Moon's orbital incline were 0 degrees instead of 5, what would be the most likely outcome?

• Lunar eclipses would last for a shorter duration.

• Lunar eclipses would become impossible.

• Only penumbral eclipses would occur.

• We would experience a lunar eclipse every full moon.

Multiple Choice

Predict what would happen to the frequency and duration of lunar eclipses if the Earth were twice as large in diameter.

• Their duration would increase, but frequency would decrease.

• They would last longer and likely occur more frequently.

• There would be no significant change.

• They would be shorter and occur less frequently.

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Summary

• A lunar eclipse happens when the full moon passes through Earth's shadow.

• Earth's shadow has a dark umbra and a lighter penumbra.

• There are three types of lunar eclipses: total, partial, and penumbral.

• The Moon's tilted orbit prevents an eclipse from happening every month.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

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