Place the new Moon
A solar eclipse needs the Moon between Earth and the Sun.
Eclipse Aligner
Change Moon phase and orbital crossing direction to distinguish eclipse alignment from ordinary phases.
Grades 3–5 · Earth Science
Your goal
Set a new Moon at 0° with the orbit crossing direction at 0°. Observe solar eclipse.
Reduced motion is on. The controls still update the scene.
quarter Moon. Moon latitude 3.54°. No eclipse. A phase alone does not guarantee an eclipse.
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The Moon's orbit tilts about 5°. This simplified latitude model marks an eclipse near a crossing at new or full Moon. The side view compresses depth and enlarges bodies separately. Vertical offsets are amplified and capped to keep misses clear and the Moon in view. Shadows illustrate alignment rather than predicting eclipse dates, paths or totality. Intermediate phases are not eclipses.
Related resources
Related simulations
Learn with Eclipse Aligner
Eclipse Aligner lets elementary students connect Moon phases with the extra alignment needed for an eclipse. Move the Moon around Earth and change where its tilted orbit crosses the Sun and Earth plane. A side view shows when the Moon can cast a shadow toward Earth or pass through Earth’s shadow, while an overhead inset identifies the phase. Try a new or full Moon that misses the line of alignment. The comparison shows why ordinary phases happen every month but eclipses require a more particular arrangement.
What to look for
Place the full Moon
A lunar eclipse needs the Moon on the opposite side of Earth from the Sun.
Miss the shadow
Change the orbit crossing direction to move a new or full Moon above or below alignment.
For teachers and curious learners
Explain why new and full Moon phases do not produce an eclipse every month. Ask students to predict what will happen, change one setting, and explain what they observe. Learn gives a starting point. Practice and Challenge offer new goals with the same scene.
A five degree sinusoidal orbital latitude and simplified eclipse threshold illustrate alignment. Enlarged bodies, vertical offsets, shadow lengths and orbital distances use separate drawing scales. This is not an eclipse predictor.