Moon Phases SimulatorDrag the Moon around Earth, and see each phase from both views.
First quarter.50% lit.
Day 7.4 of 29.53. It rises about noon and sets about midnight.
Earth and the Moon are drawn far larger and closer together than they are, so you can see them. At true scale, the Moon would be 30 Earth-widths away.
The Moon's phase is how much of its sunlit half you can see from Earth. The Sun always lights half the Moon. As the Moon circles Earth every 29.5 days, you see that lit half from a changing angle.
Try this.
- Drag the Moon to Full. Where are the Sun, Earth and Moon? Now read what time a full moon rises.
- Set the time to noon. Which phases can you see in the daytime sky?
- Choose Southern Hemisphere. What happens to the crescent?
- Press Tonight's Moon, then go outside after dark and check it.
See tonight's Moon, where you are.
Sol shows the Moon's real phase, where it stands in your sky, and when the next full moon rises.
The phase of the MoonMoonrise and moonsetWhat a supermoon is
What's happening.
What causes the phases of the Moon?
The Sun lights one half of the Moon at all times. The phase is how much of that lit half faces you. At new moon, the lit half faces away from Earth. At full moon, it faces you. Between them you see part of it, which is why the phases change slowly and in order.
What are the eight phases in order?
New moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, and waning crescent. Waxing means growing, and waning means shrinking.
What time does each phase rise?
A new moon rises at about 6 AM, a first quarter at about noon, a full moon at about 6 PM, and a third quarter at about midnight. The Moon rises about 50 minutes later each day, because it moves along its orbit as Earth turns.
How long does a full cycle take?
From one new moon to the next takes 29.5 days. The Moon finishes one orbit in 27.3 days, but Earth has moved around the Sun by then, so the Moon needs about two more days to line up again.
Why does the Moon look different in the Southern Hemisphere?
People there see it upside down compared with people in the north. A waxing crescent lit on the right in New York is lit on the left in Sydney. Near the equator, a crescent can look like a smile.
Why do we always see the same side?
The Moon turns once on its axis in the time it takes to go around Earth, so one face always points at us. The far side is not dark. It gets as much sunlight as the near side, and at new moon it is fully lit.
Common mix-ups.
Earth's shadow falls on the Moon only during a lunar eclipse. At first quarter, Earth's shadow points far from the Moon, and half the Moon is still dark. That dark half is the Moon's own night.
The Moon is above the horizon for about 12 hours a day, whatever the phase. A first-quarter moon is up all afternoon. Set the time to 3 PM in the simulator and look for it.
Every part of the Moon gets about two weeks of sunlight and two weeks of night. The far side is only far from us.
Clouds can hide the Moon, but the shape of a phase stays the same night after night, wherever you stand on Earth.
For teachers.
Grades 3 to 8. 15 to 30 minutes. Students need no account, and the page collects nothing about them.
Standards
- MS-ESS1-1
- Model the Earth-Sun-Moon system to describe lunar phases
- 1-ESS1-1
- Describe patterns of the Sun and Moon that can be predicted
- England, Year 5
- Describe the movement of the Moon relative to the Earth
Discussion questions, with answers
- Why can't you see a new moon?
- Its lit half faces away from Earth, and it stands close to the Sun in the sky.
- Where in its orbit is the Moon at full?
- On the far side of Earth from the Sun.
- When is a first-quarter moon highest in the sky?
- At about sunset. It rises near noon and sets near midnight.
- If the Moon were lit from every side at once, what would happen to its phases?
- They would stop. Phases exist only because sunlight comes from one direction. Lit from all sides, the Moon would look full all the time.
Embed it in your class page
Paste this into Google Classroom, Canvas, Schoology or your own site.
<iframe src="https://initial.app/embed/moon-phases" title="Moon Phases Simulator" width="100%" height="760" style="border:0" loading="lazy" allowfullscreen></iframe>
<p><a href="https://initial.app/moon-phases">Moon Phases Simulator</a> from Initial</p>
