Crimson Shadows Teacher Guide Teacher Guide • Section 1
CRIMSON SHADOWS
Unveiling the Mechanics of Lunar Eclipses & Rayleigh Scattering
Suggested Grade Middle / High School
NGSS Alignment & Big Ideas
MS-ESS1-1: Develop and use a model of the Earth-sun-moon system to explain the cyclic patterns of lunar phases, eclipses of the sun and moon.
Crosscutting Concept (Systems & Models): Explain Rayleigh scattering, atmospheric refraction, and solar/lunar geometries.
Learning Objectives
Model: Demonstrate the spatial geometry of the Sun, Earth, and Moon during solar/lunar eclipses.Analyze: Explain Rayleigh scattering and how atmospheric refraction turns the Moon deep red.Contrast: Contrast solar and lunar eclipses regarding visibility windows, frequency, and duration.
Lesson Pacing Outline
10m
1. Engage Hook with Blood Moon imagery & atmospheric lens.
15m
2. Explain Slides: umbra, penumbra, & scattering geometry.
35m
3. Explore Model orbit shadows & perform Rayleigh milk lab.
15m
4. Elaborate Synthesize; compare solar/lunar mechanics.
10m
5. Evaluate Administer Formative Quiz & collect exit tickets.
Essential Science Background
Rayleigh Scattering: Atmospheric gas particles are smaller than the wavelengths of visible light. When sunlight hits these particles, shorter wavelengths (blue/violet) scatter widely, which is why our sky looks blue. Longer wavelengths (red/orange) pass straight through with minimal scattering.
The Crimson Refraction: During a total lunar eclipse, direct sunlight is blocked by Earth. However, sunlight grazing Earth passes through our thick atmosphere. Blue light is scattered away, while orange and red light is bent (refracted) inward by the atmosphere, focusing onto the Moon. To an observer on the Moon, Earth would appear surrounded by a glowing red ring of all the world's sunrises and sunsets!
CRIMSON SHADOWS Teacher Guide PAGE 1 OF 3
Teacher Guide • Section 2
Lab Setup & Experiment Facilitation
Physical Modeling Setup Details
Materials Checklist (Per Team)
Clear Vessel: Glass flask or smooth plastic beaker (500mL+).Scattering Agent: Liquid milk or cream (1-2 drops!).Flashlight: High-powered white LED flashlight or phone.Light Screen: Blank white index card/cardstock.Model Spheres: Large ball (Earth, ~4") & Small ball (Moon, ~1").
Setup Guidelines
The Dilution Key: Add only one drop of milk at a time. It must be a faint, translucent bluish-gray mist. Over-milked water blocks light entirely.Total Darkness: Block out all window light and turn off classroom lights. The Rayleigh scattering blue glow is best observed in near-total darkness.
Step-by-Step Lab Facilitation
Step 1
Establish Orbit & Shadow Geometry: Have students place the flashlight (Sun), the large ball (Earth), and the small ball (Moon) in a straight line. Adjust spacing until the Moon is fully submerged in the Earth's dark central shadow (umbra). Point out that this matches a Lunar Eclipse alignment (S-E-M).
Step 2
Analyze the Scattered Blue Light: Darken the room. Students shine the white flashlight straight through the side of the clear bottle. Looking at the bottle from the side , they should notice a cool bluish tint. Ask: "Why does the water glow blue?" (Small suspended particles scatter blue waves).
Step 3
Capture the Transmitted Red Light: Students place the white index card directly behind the opposite end of the bottle, capturing the transmitted light beam. They will observe a warm, amber-red circle. Explain that this is the light left over after blue is filtered—the light that bends around Earth to light up the Moon!
CRIMSON SHADOWS Teacher Guide PAGE 2 OF 3
Teacher Guide • Section 3
Discussion Prompts & Assessment Keys
Classroom Discussion Starters
• Connection: "What is the connection between why our sky is blue during the day and why the Moon turns red at night?" (Both are caused by Rayleigh scattering. Daytime sky is blue because we look at scattered blue light. The eclipsed Moon is red because we are looking at the transmitted, filtered red light).
• No Atmosphere Scenario: "If Earth had no atmosphere, what would a total lunar eclipse look like?" (Pitch black. No atmosphere means no light is refracted/scattered, leaving the Moon in absolute darkness).
Master Answer Keys
Student Lab Sheet Keys
Alignment Drawing: Sun → Earth → Moon in a straight line. Moon sits in the central dark cone of Earth's shadow (umbra).Rayleigh Test (Side): Light viewed from side shows a pale blue-white glow (represents daytime Rayleigh scattering).
Rayleigh Test (Screen): The projected light spot shows an orange-red glow (represents sunlight filtered by Earth's atmosphere).No Atmosphere: The Moon would appear completely dark during an eclipse because there are no gases to refract/filter light.
Formative Quiz Keys
Section 1: Multiple Choice
C: Sun, Earth, Moon (Lunar Eclipse alignment)B: Rayleigh scattering (removes shorter blue waves)A: Visible from the entire night side of EarthD: Central dark shadow (umbra); outer shadow (penumbra)
Section 2: Comparison Table Highlights
• Alignment: Solar (S-M-E) vs. Lunar (S-E-M)
• Duration: Solar (~7m max) vs. Lunar (several hours)
• Frequency: Solar path is narrow; Lunar visible globally
• Phase: Solar (New Moon) vs. Lunar (Full Moon)
CRIMSON SHADOWS Teacher Guide PAGE 3 OF 3
Shadow Play Lab Sheet Student Lab Activity
SHADOW PLAY: LUNAR ECLIPSES
Student Name
Date
Part 1: Space Alignment & Geometry
When the Earth, Sun, and Moon align in deep space, dramatic shadows are cast. In this activity, you will model these alignments using spheres, trace the boundary of Earth's shadow, and analyze how distance affects shadow size.
1. Sketching the Alignment
In the workspace below, sketch the alignment of the Sun , Earth , and Moon during a total lunar eclipse . Label the three celestial bodies and draw the light rays originating from the Sun, highlighting where the shadow zone falls.
Sketch Alignment Here
Label: Sun, Earth, Moon
2. Identifying the Shadow Zones
A planet’s shadow has two distinct parts: the dark central core and the lighter outer ring. Based on your physical ball model observations, answer the questions below.
A. Defining the Shadow Regions
Define the Umbra in your own words:
Define the Penumbra in your own words:
B. Spatial Observations
What happens to the dark umbra shadow as you pull the Moon model further away from Earth?
In which of these two shadow regions must the Moon sit to experience a Total Lunar Eclipse?
Crimson Shadows Student Lab Sheet PAGE 1 OF 2
Student Lab Activity
Part 2: The Rayleigh Scattering Experiment
Now we will investigate why the Moon turns blood-red instead of going completely black in Earth's shadow. By passing white light through water containing suspended milk fat particles, we will model how Earth's atmosphere alters sunlight.
3. Data & Observations Table
Viewing Position Observed Color / Appearance Atmosphere Connection Position A: Looking at the water vessel from the SIDE. This represents the light scattered outward by gas in our atmosphere. What color of the daytime sky matches this? Position B: Looking at the projected light beam on the white cardstock screen behind the container.
| This represents the light transmitted (filtered and bent) through Earth's atmosphere during an eclipse. What color does the Moon turn? |
Eclipse Showdown Quiz Formative Assessment
ECLIPSE SHOWDOWN QUIZ
Student Name
Date
1 Multiple Choice Questions
1. What is the spatial alignment during a Total Lunar Eclipse?
A) Earth → Sun → Moon B) Sun → Moon → Earth C) Sun → Earth → Moon
2. Why does the Moon turn red instead of going black in the shadow?
A) Friction heating on the Moon's dust B) Earth's atmosphere filters blue and bends red light C) Red particles reflecting solar storms
3. Who can observe a total lunar eclipse when it occurs?
A) Anyone living on the night side of the Earth B) Only individuals within a narrow 100-mile ground path C) Only observers near Earth's polar rings
4. What is the central dark core of a celestial shadow zone called?
A) Penumbra B) Scattering ring C) Umbra
2 Comparative Eclipse Analysis
Feature Solar Eclipse Lunar Eclipse 1. Alignment (S-M-E or S-E-M) 2. Required Moon Phase (New, Full, etc.) 3. Approximate Duration (Minutes vs. Hours) 4. Global Visibility Area (Narrow path vs. Whole hemisphere)
3 Atmospheric Mechanics Explanation
An astronaut stands on the Moon during a Total Lunar Eclipse, looking back at Earth. Describe what they see in the sky and why it is colored this way. Incorporate the terms refraction and Rayleigh scattering .
Crimson Shadows Formative Assessment ECLIPSE SHOWDOWN QUIZ
Crimson Shadow Exit Tickets Exit Ticket • Formative Check
CRIMSON SHADOWS
Student Name
Date
1. If Earth had absolutely no atmosphere, what would a total lunar eclipse look like?
A) Solid dark red B) Pitch black / invisible C) Bright glowing blue
2. In your own words, describe why Rayleigh scattering causes the Moon to turn deep red during an eclipse.
© Classroom Science Resources Ticket A • Formative Check
CUT HERE FOR 2 TICKETS
Exit Ticket • Formative Check
CRIMSON SHADOWS
Student Name
Date
1. If Earth had absolutely no atmosphere, what would a total lunar eclipse look like?
A) Solid dark red B) Pitch black / invisible C) Bright glowing blue
2. In your own words, describe why Rayleigh scattering causes the Moon to turn deep red during an eclipse.
© Classroom Science Resources Ticket B • Formative Check
Crimson Shadows Presentation Middle / High School Science MS-ESS1-1 System Models
CRIMSON SHADOWS
Unlocking the celestial geometry of Lunar Eclipses and the optical mechanics of the Blood Moon.
Goal 1: Model Alignment Geometry
Goal 2: Solve the Rayleigh scattering puzzle
THE GEOMETRY OF SHADOWS
01 / Alignment
Lunar Eclipse Alignment
A lunar eclipse occurs when the Earth blocks direct solar light from illuminating the Moon. For this to happen, the bodies must align in a straight line:
SUN → EARTH → MOON
The Double Shadow
Earth's solid structure blocks sunlight and casts two distinct, concentric cones of shadow in deep space:
•
Umbra: The dark, inner core where light is blocked completely.
•
Penumbra: The lighter, outer fan where light is partially blocked.
Crimson Shadows Lesson Slides
THE BLOOD MOON MYSTERY
02 / Scattering
Why Does the Moon Turn Red?
If Earth completely blocks the Sun, why isn't the Moon invisible? The answer lies in Earth's atmosphere acting as a giant optical lens:
1. Short Waves Scattered
Short wavelengths (blue and violet) hit atmospheric particles and scatter away in all directions.
2. Long Waves Refracted
Long wavelengths (red and orange) travel clean through and are bent inward onto the Moon.
Rayleigh Scattering
This optical process is the exact reason why:
Our skies are blue during the day
Our sunsets are crimson at dusk
The eclipsed Moon turns red
"The Moon is lit by the glow of every sunset and sunrise happening on Earth at once!"
Crimson Shadows Lesson Slides
THE ECLIPSE SHOWDOWN
03 / Comparison
Characteristic Solar Eclipse Lunar Eclipse Alignment Structure Sun → Moon → Earth Sun → Earth → Moon Lunar Phase Required New Moon Full Moon Observer Path Width
