Solar & Lunar Eclipses

About this simulation

This simulation shows the Moon's tilted orbit around Earth, with the umbra and penumbra drawn as shadow cones. Auto orbit runs the system, or students untick it and set the Moon phase, the node offset and the Moon distance. Readouts report the phase, how far the Moon is above or below the orbit plane, and whether an eclipse is happening. Camera views include a side view and a whole-system view. Teachers can use it to explain why eclipses are rare and why some solar eclipses are annular. Note that sizes and tilt are exaggerated.

What students can explore

Leave Auto orbit on and watch the Eclipse now readout as the Moon circles Earth.
Switch to Side view to see how the Moon's orbit is tilted above and below the plane.
Untick Auto orbit and set Moon phase to 0 degrees, then change Node offset until a solar eclipse starts.
Set Moon phase to 180 degrees and find a lunar eclipse.
Change Moon distance and compare a total with an annular solar eclipse.

Learning objectives

1Explain why a solar eclipse needs a new Moon and a lunar eclipse needs a full Moon.
2Describe how the tilt of the Moon's orbit makes eclipses uncommon.
3Define the nodes where the Moon crosses Earth's orbital plane.
4Compare total and annular eclipses using the Moon's distance.

Questions teachers ask

Is the eclipse simulation free to use?

Yes. It is completely free and runs in any modern web browser, including on interactive whiteboards, tablets, Chromebooks and phones. There is nothing to install and no sign-up or account is needed.

Why is there not an eclipse every month?

The Moon's orbit is tilted about 5 degrees to Earth's orbit, so at most new and full Moons it passes above or below the shadow. An eclipse needs the alignment to happen near a node.

What is an annular eclipse?

When the Moon is farther from Earth it looks slightly smaller than the Sun and cannot cover it completely, leaving a bright ring. Raise the Moon distance slider to see the shadow change.

How do I use the eclipse simulation?

Let Auto orbit run to see the pattern, then untick it and set the phase and node offset yourself. Use the camera views to check alignment from the side.

Embed this simulation

Drop it into your LMS, blog, or class site — free.

<iframe src="https://kiwibee.io/en/simulations/eclipses-3d-simulation/embed" title="Solar &amp; Lunar Eclipses | KiwiBee" loading="lazy" allowfullscreen style="width:100%;height:min(70vh,620px);min-height:420px;border:0;border-radius:16px"></iframe>

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