Why a Lunar Month Is Longer Than an Orbit
Written by Adi Ackerman, Head Teacher
"Why a Lunar Month Is Longer Than an Orbit" is written for 8th Grade (Ages 13-14), and it covers NGSS MS-ESS1-1. A 7th grader who is already steady on Earth and space can use it too, and an older student can use it as a short review.
2 pages in this set
8th grade science worksheet: label a diagram showing why full moon to full moon takes 29.5 days while one orbit takes 27.3. Answer key included. Part of our moon phases, eclipses and seasons earth and space collection. Aligned to NGSS standards.
How do I use this worksheet?
Start with the lunar month diagram, then the tilted orbit sheet. Use the 2025 timeline to test the model, and add the pendulum sheet as evidence of rotation.
What students will practice
- Students will compare the 27.3 day orbit with the 29.5 day cycle from full moon to full moon.
- Students will label an orbit diagram and draw the Moon's path.
- Students will explain how Earth's motion around the Sun adds about 2 days.
Curriculum Links
Next Generation Science Standards
Science · 8th Grade
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FAQ
How do I use this moon phases, eclipses and seasons worksheet?
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Start with the lunar month diagram, then the tilted orbit sheet. Use the 2025 timeline to test the model, and add the pendulum sheet as evidence of rotation.
What does this worksheet teach?
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Label a diagram showing why full moon to full moon takes 29.5 days while one orbit takes 27.3. The directions on the page read: Read the text and study the diagram. Write the letter from the diagram in the box next to each label. Then draw an arrow along the Moon's orbit from E to F. An answer key is included.
Can I use this moon phases, eclipses and seasons worksheet for homeschool or classroom?
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Yes, both. We made it for 8th grade Earth and space, and it works the same at home or at school. At home, a student can work through it alone and then go over it with you, which shows quickly what is solid and what needs another look. In class it works as independent practice, homework or a warm-up, and you can print one copy or a full set.
What is an eclipse season?
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An eclipse season is a stretch of a few weeks when the Moon's nodes line up with the Sun, so both solar and lunar eclipses can happen. In 2025, a lunar eclipse on March 14 was followed by a solar eclipse on March 29. The timeline sheet places all four 2025 eclipses.
Why does a lunar eclipse need a full moon?
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A lunar eclipse happens when Earth's shadow falls on the Moon. That requires Earth to be between the Sun and the Moon, which is the full moon position. A solar eclipse needs a new moon instead.
How does a Foucault pendulum show that Earth spins?
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The pendulum keeps swinging in the same direction, but the floor under it turns with Earth. At the North Pole the swing turns about 15 degrees per hour, and at the equator it does not turn. The pendulum sheet graphs the rate by latitude.
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Worksheet Details
| Grade | 8th Grade |
| Subject | Science |
| Topic | Earth and Space |
| Standard | MS-ESS1-1 |
| Pages | 2 pages |
| Difficulty | Medium |
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