Lunar Eclipses

Lunar Eclipses

Middle School

​

Learning Objectives

• Describe the rotational and orbital relationships between the Earth, Moon, and Sun.

• Explain how the tilt of Earth's axis causes the seasons.

• Model the specific alignments of the Sun, Earth, and Moon that result in lunar and solar eclipses.

• Justify why eclipses are rare events and do not occur every month.

Key Vocabulary

​

Lunar Eclipse

An event where the Moon passes directly behind Earth and into its shadow, causing it to darken.

​

Solar Eclipse

An event where the Moon passes between the Sun and Earth, blocking the Sun's light from view.

​

Orbit

The curved path of a celestial object as it revolves around a star, planet, or another moon.

​

Moon Phase

The shape of the Moon's directly sunlit portion as it is seen from our viewpoint on Earth.

​

Rotation

The specific action of an object, like a planet, turning or spinning around its own center or axis.

​

Revolution

The movement of one celestial object in a fixed path or orbit around a center or another object.

Key Vocabulary

​

Axial Tilt

The angle between a planet's rotational axis and its orbital axis.

​

Umbra

The fully shaded inner region of a shadow cast by an opaque object.

Earth's and Moon's Motion

• Earth rotates on its axis and revolves around the Sun.

• The Moon rotates on its axis while revolving around the Earth.

• We always see the same side of the Moon from Earth.

Multiple Choice

Which statement correctly describes the two main motions of the Earth?

• Rotating on its axis and revolving around the Sun.

• Revolving around the Moon and rotating on its axis.

• Moving toward and away from the Sun.

• Orbiting the Sun and orbiting the Moon.

Multiple Choice

What is the primary difference between the Moon's revolution and Earth's revolution?

• The Moon revolves around the Earth, while the Earth revolves around the Sun.

• The Earth revolves around the Moon, while the Moon revolves around the Sun.

• The Moon rotates on its axis, but the Earth does not.

• Both the Earth and the Moon only revolve around the Sun.

Multiple Choice

Based on the motions of the Earth and Moon, what is the best explanation for why we always see the same side of the Moon?

• The Moon completes one rotation on its axis in the same amount of time it takes to revolve once around the Earth.

• The Moon does not rotate on its axis, so the same side always faces Earth.

• The Earth's gravity is so strong that it prevents the Moon from rotating.

• The Earth rotates at the same speed that the Moon revolves around it.

​

​

The Cause of Moon Phases

• Moon phases are not caused by the Earth's shadow hitting the Moon.

• They happen because of our changing view of the Moon’s sunlit half.

• As the Moon orbits Earth, we see different angles of its illuminated surface.

• The cycle repeats from a New Moon to a Full Moon and back.

Multiple Choice

What is the fundamental cause of the Moon's phases?

• Our changing view of the Moon's sunlit side.

• The shadow of the Earth falling on the Moon.

• The Moon creating its own light in a cycle.

• Clouds on Earth blocking our view of the Moon.

Multiple Choice

How does the Moon's movement result in the cycle of phases from New Moon to Full Moon?

• As the Moon orbits Earth, we see different amounts of its illuminated half.

• The Earth's rotation makes the Moon appear to change shape each night.

• The Moon moves closer to and farther from the sun during its cycle.

• The Earth's shadow blocks different parts of the Moon as it moves.

Multiple Choice

If the Moon stopped orbiting the Earth and remained in a fixed position, what would be the most likely outcome regarding its phases?

• We would continuously see the same single phase of the Moon.

• The Moon would always appear as a Full Moon.

• The Moon would cycle through its phases much more quickly.

• The Earth's shadow would permanently cover the Moon.

​

​

The Cause of Seasons

Summer

• A hemisphere tilted towards the Sun receives more direct and concentrated sunlight.

• The higher intensity of sunlight leads to warmer temperatures and longer days.

• The Earth's tilt, at about 23.5 degrees, is the primary cause of summer.

Winter

• A hemisphere tilted away from the Sun receives less direct, spread-out sunlight.

• The lower intensity of sunlight leads to cooler temperatures and shorter days.

• The distance from the Sun does not cause winter; the planet's tilt does.

Multiple Choice

What is the primary reason the Earth experiences seasons like summer and winter?

• The tilt of the Earth on its axis.

• The Earth's changing distance from the Sun.

• The variation in the length of the days.

• The amount of cloud cover in a hemisphere.

Multiple Choice

Why does a hemisphere experience warmer temperatures during summer?

• The sunlight is more direct and concentrated, leading to higher intensity.

• The sunlight is less direct and spread out, leading to lower intensity.

• The hemisphere is physically closer to the Sun, increasing heat.

• The atmosphere in that hemisphere becomes thinner, trapping less heat.

Multiple Choice

If the Earth's axis were not tilted, what would be the most likely consequence?

• Summers would become significantly hotter and winters much colder.

• The entire planet would experience winter conditions year-round.

• One hemisphere would be permanently hot and the other permanently cold.

• Temperatures in each hemisphere would be more uniform throughout the year.

Lunar Eclipses Explained

• A lunar eclipse occurs when the Sun, Earth, and Moon are aligned.

• The Moon passes directly into the shadow cast by the Earth.

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

Multiple Choice

Which statement best describes the event of a lunar eclipse?

• The Moon passes into the shadow cast by the Earth.

• The Sun moves directly between the Earth and Moon.

• The Earth passes into the shadow cast by the Moon.

• The Moon's gravitational pull on Earth is strongest.

Multiple Choice

What is the relationship between the umbra and the penumbra in Earth's shadow during a lunar eclipse?

• The umbra is the lighter, outer part of the shadow, and the penumbra is the darker, central part.

• The umbra and penumbra are two separate shadows cast by the Earth and Moon, respectively.

• The umbra is the part of the shadow that causes solar eclipses, while the penumbra causes lunar eclipses.

• The umbra is the darker, central part of the shadow, and the penumbra is the lighter, outer part.

Multiple Choice

If the Sun, Earth, and Moon are aligned so that the Moon passes only through Earth's lighter penumbra, what would be the most likely outcome?

• A total eclipse where the Moon becomes completely dark.

• A partial eclipse where the Moon only dims slightly.

• No eclipse would be visible from Earth.

• A solar eclipse would occur instead.

Solar Eclipses Explained

• A solar eclipse is when the Moon is between the Sun and Earth.

• This alignment only happens during the New Moon phase.

• The Moon's shadow creates total or partial eclipses on Earth.

Multiple Choice

Which statement accurately describes the arrangement of the Sun, Earth, and Moon during a solar eclipse?

• The Moon is positioned between the Sun and Earth.

• The Earth is positioned between the Sun and Moon.

• The Sun is positioned between the Earth and Moon.

• The Moon is behind the Earth and away from the Sun.

Multiple Choice

Why do solar eclipses not happen every month during other lunar phases?

• The alignment can only occur during the New Moon phase.

• The alignment can only occur during the Full Moon phase.

• The Moon's shadow is not dark enough at other phases.

• The Earth is tilted away from the Sun at other phases.

Multiple Choice

If the Moon is in the correct position between the Sun and Earth during its New Moon phase, what is the predicted effect on Earth?

• The Moon's shadow will be cast on a specific area of Earth.

• The Earth's shadow will be cast on the surface of the Moon.

• The entire planet will experience a brief period of darkness.

• The Sun's light will become permanently dimmer.

​

​

Why Eclipses Are Rare

• The Sun, Earth, and Moon align during every new and full moon.

• However, the Moon's orbit is tilted by about 5 degrees from Earth's orbit.

• This tilt causes the Moon's shadow to usually miss the Earth.

• Eclipses only happen when the alignment is perfect with the orbital planes.

Multiple Choice

What is the primary reason that eclipses do not happen every month?

• The Moon's orbit around Earth is tilted.

• The Earth's orbit around the Sun is circular.

• The Moon is much smaller than the Sun.

• The Earth rotates on its axis once a day.

Multiple Choice

How does the 5-degree tilt in the Moon's orbit affect the alignment of the Sun, Earth, and Moon?

• It causes the Moon's shadow to pass above or below Earth.

• It makes the Moon orbit Earth more slowly.

• It changes the timing of the seasons on Earth.

• It makes the Sun appear larger in the sky.

Multiple Choice

Considering the usual effect of the Moon's tilted orbit, what must happen for an eclipse to occur?

• The Sun, Earth, and Moon must all be perfectly aligned on the same plane.

• The Moon must be in its 'new' or 'full' phase.

• The Earth must be at its closest point to the Sun.

• The Moon's speed must increase to catch up with Earth.

​

Common Misconceptions

Misconception	Correction
Seasons are caused by how close Earth is to the Sun.	Seasons are caused by the 23.5-degree tilt of Earth's axis.
We have a lunar eclipse every time there is a full moon.	Eclipses are rare because the Moon's orbit is tilted.
The 'dark side' of the Moon never sees sunlight.	All sides of the Moon receive sunlight; it is more accurately called the 'far side'.

​

Summary

• Earth's rotation causes day and night; its revolution around the Sun defines a year.

• The phases of the Moon are caused by our changing view of its sunlit half.

• Seasons are a result of Earth's axial tilt, not its distance from the Sun.

• Eclipses are rare because the Moon's orbit is tilted relative to Earth's orbit.

Poll

On a scale of 1-4, how confident are you about explaining the difference between a solar and lunar eclipse?

• 1 - Not confident at all

• 2 - A little confident

• 3 - Mostly confident

• 4 - Very confident