Moon Phases
📖 Learn
Have you ever noticed that the Moon looks different each night? Sometimes it's a bright, full circle. Other times it's a thin sliver, or you can't see it at all! These changes are called moon phases, and they happen because of how the Moon orbits Earth.
🌙 Why Does the Moon Change Shape?
The Moon doesn't actually change shape! It's always a sphere. What changes is how much of the lit side we can see from Earth. The Sun always lights up half of the Moon, but as the Moon orbits Earth, we see different amounts of that lit half.
Understanding the Moon's Orbit
The Moon takes about 29.5 days to complete one full cycle of phases. This is called a lunar cycle or lunar month. During this time, the Moon travels completely around Earth once.
The 8 Moon Phases Explained
New Moon
The Moon is between Earth and the Sun. The lit side faces away from us, so we can't see the Moon at all.
0% VisibleWaxing Crescent
A small sliver of light appears on the right side. "Waxing" means growing bigger. The Moon is starting to show!
1-49% VisibleFirst Quarter
Half of the Moon is lit (the right half). It's called "quarter" because the Moon is one-quarter of the way through its cycle.
50% VisibleWaxing Gibbous
More than half is lit but not quite full. "Gibbous" means more than half. The lit area keeps growing!
51-99% VisibleFull Moon
Earth is between the Sun and Moon. We see the entire lit side—a beautiful, bright, full circle!
100% VisibleWaning Gibbous
Still more than half lit, but shrinking. "Waning" means getting smaller. The dark area grows from the right.
99-51% VisibleLast Quarter
Half of the Moon is lit (the left half this time). The Moon is three-quarters through its cycle.
50% VisibleWaning Crescent
Just a thin sliver remains on the left side. The Moon is almost done with its cycle, heading back to New Moon.
49-1% Visible💡 Examples
Test your knowledge of the moon phases with this interactive game!
What phase is this Moon?
✏️ Practice
Answer these questions to check your understanding of moon phases.
✅ Check Your Understanding
🌑 New Moon
Moon between Sun and Earth. We see the dark side (0% visible).
🌕 Full Moon
Earth between Sun and Moon. We see the entire lit side (100% visible).
📈 Waxing
The lit portion is growing (getting bigger) each night.
📉 Waning
The lit portion is shrinking (getting smaller) each night.
🌙 Crescent
Less than half of the Moon is lit (a thin curved slice).
🌔 Gibbous
More than half of the Moon is lit (but not yet full).
🎯 Key Takeaways
- The Moon doesn't change shape—we just see different amounts of its lit side
- The lunar cycle takes about 29.5 days to complete
- There are 8 main phases: New, Waxing Crescent, First Quarter, Waxing Gibbous, Full, Waning Gibbous, Last Quarter, and Waning Crescent
- Waxing = growing larger, Waning = getting smaller
🚀 Next Steps
- Go outside and observe the Moon tonight! What phase do you think it's in?
- Keep a Moon journal for a month and sketch the Moon each night
- Review this lesson and try the game again to improve your score
- Return to the Solar System unit to explore more about our cosmic neighborhood