🌑 ☀️ 🌕 🔭
Simulation

Eclipse Alignment

Can you create an eclipse by lining up the Sun, Earth, and Moon?

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Driving Question
Why does the Moon reach new moon and full moon every month, but eclipses only happen sometimes?
🔬 Learning Science Focus Spatial Reasoning Productive Struggle Guided Inquiry
📋 MA STE Standards · Grade 6 6.MS-ESS1-1a SP2: Modelling SP4: Analyzing Data
① Evidence
② Align the System
③ Deep Time
④ Quiz
Mission Briefing

What You Need to Know First

Before you touch the controls, read these three facts. They are the rules of the simulation.

Solar Eclipse
New Moon + Node
The Moon must be between the Sun and Earth; that is a new moon. It also must be near a node, the point where its tilted orbit crosses Earth's orbital plane. Both must be true at the same time.
Lunar Eclipse
Full Moon + Node
Earth must be between the Sun and Moon; that is a full moon. The Moon must also be near a node so Earth's shadow actually reaches it. Phase alone is not enough.
Most Months
Shadow Misses
The Moon's orbit is tilted about 5 degrees relative to Earth's orbital plane. Most new and full moons, the Moon is slightly above or below the plane; and the shadow passes without hitting.
The core idea: A new moon or full moon is not enough. The Moon also has to be near a node.
Locked
Unlock all three observations to begin the eclipse investigation.
Lab

Eclipse Alignment

Use the controls below to set up the Sun-Earth-Moon system. Adjust all three dials and watch the result change in real time.

🔒 Unlock the three observation cards above to begin the lab.
Eclipse Type
Moon Phase
Moon Height
👆 Select an eclipse type, moon phase, and moon height to begin.
Guided Challenges

Three Challenges

Use the lab controls above to solve each challenge. Read the goal, set the controls, and watch the result. You can revise as many times as you like.

0 / 3 completed
1
Solar Eclipse
2
Lunar Eclipse
3
Why Not Every Month?
Challenge 1
Create a total solar eclipse.
Think carefully: which phase puts the Moon between the Sun and Earth? And where does the Moon need to be in its orbit for the shadow to actually connect?
Solar Eclipse Achieved
New moon + near a node = the Moon's shadow reaches Earth. Both conditions had to be true at the same time.
Challenge 2 Locked
Create a lunar eclipse.
This time Earth casts the shadow. Which phase puts the Moon on the far side of Earth from the Sun? What else has to be true?
Lunar Eclipse Achieved
Full moon + near a node = Earth's shadow falls on the Moon. The Moon had to be on the far side of Earth and near the orbital plane.
Challenge 3 Locked
Create a month with no eclipse.
The right phase is there; but the shadow still misses. Show what happens most months when the Moon is above or below the orbital plane.
No Eclipse Month Achieved
Even with the correct phase, the Moon's tilted orbit causes the shadow to miss. Most months work this way.
Locked
Complete all investigation challenges to unlock the scientific explanation.
Locked
Solve all three challenges in the lab above to reveal what the simulation just showed you.
Discovery Summary

What You Found Out

Three things the lab just showed you. Each one connects to a challenge you solved.

Moon Phase✓
In Challenge 1 you needed a new moon, the only phase that puts the Moon between the Sun and Earth.
In Challenge 2 you needed a full moon, the only phase that puts Earth between the Sun and Moon.
Quarter moon failed both. The geometry has to be right from the start.
Orbital Nodes✓
In Challenge 3 the phase was correct; but the shadow still missed.
The Moon's orbit is tilted about 5 degrees, so it usually passes above or below the orbital plane. The shadow misses Earth or the Moon entirely.
Eclipses only happen when the Moon is near a node, one of two places where its orbit crosses the plane.
Shadow Zones✓
Even when an eclipse happens, not everyone sees the same thing.
The umbra is the darkest part of the shadow, observers inside it see a total eclipse.
The penumbra is the outer shadow, observers there see only a partial eclipse.
Your location relative to the shadow determines what you experience.
The big takeaway: Moon phase creates the possibility. Node alignment makes the eclipse happen.
Locked
Complete the three eclipse alignment challenges to unlock the Deep Time cinematic.
Phase 3

Deep Time

What looks permanent in the sky is only temporary on geologic time scales. The Moon is slowly drifting away from Earth; and that quietly changes what eclipses look like.

Ready

Model note: This animation compresses hundreds of millions of years into a few seconds. Dates are estimates based on the Moon moving away from Earth about 3.8 cm per year.

Ready to begin

A 10-second journey through deep time

Watch how the Moon’s slow outward drift quietly transforms what eclipses look like across millions of years.

Locked
Complete the Deep Time animation to unlock the checkpoint quiz.
Locked
Finish the Deep Time animation and click Continue to Quiz to unlock the checkpoint.
Check Your Understanding

Checkpoint

5 questions about eclipse alignment, moon phase, orbital tilt, nodes, and shadows.

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