How a Solar Eclipse Works

What to say / Spoken Script

Hello class! Today we are going to learn how a solar eclipse works. A solar eclipse is a spectacular astronomical event. First, let us introduce the three main players in our system: on the far left of the screen is the huge, shining Sun; on the far right is our home planet, Earth; and right in the middle is the Moon, revolving around the Earth. Usually, the Moon's orbit is slightly tilted, allowing sunlight to shine directly on Earth, bringing daylight to our world.

What to do / Action Guide

Guide students to identify the orange Sun on the left, the blue-green Earth on the right, and the grey Moon in its orbit in the middle. Note the straight propagation path of the light rays.

Pedagogical Tips

You can ask the students: Among the Sun, Earth, and Moon, which is the star, which is the planet, and which is the satellite? Remind them that the actual distance and scale in space are far larger than shown in this diagram.

What to say / Spoken Script

Now, the Moon has moved directly between the Sun and Earth, so that the three celestial bodies are perfectly aligned in a straight line! Since light travels in straight lines, the Moon—which is an opaque body—blocks the light rays coming from the Sun. We can see a long, cone-shaped shadow cast behind the Moon, which projects onto a specific region on the surface of the Earth.

What to do / Action Guide

Show students how the Moon aligns perfectly between the Sun and Earth, and notice the shadow cone extending from the back of the Moon to the Earth.

Pedagogical Tips

Ask the students: Around what time in the lunar calendar does a solar eclipse occur? (New Moon). Why doesn't a solar eclipse happen every month on the New Moon? (Because the Moon's orbit is tilted at about 5 degrees relative to Earth's orbit around the Sun).

What to say / Spoken Script

Finally, let's take a closer look at the Moon's shadow. The shadow cast by the Moon actually has two distinct parts. The central region receives absolutely no sunlight and is dark black; this is called the 'Umbra'. People on Earth located within this narrow umbra zone will experience a 'Total Solar Eclipse', where the Sun is completely blocked. The outer, lighter shadow region is called the 'Penumbra'. People located here will see a 'Partial Solar Eclipse'. Notice that only a small portion of the Earth can see the eclipse at any one time.

What to do / Action Guide

Point out the narrow dark shadow (Umbra) representing the total solar eclipse and the wider, lighter shadow (Penumbra) representing the partial solar eclipse on Earth's surface.

Pedagogical Tips

Ask students to summarize: Why can a solar eclipse only be seen from a specific region on Earth, rather than half the planet like a lunar eclipse? (Because the Moon is much smaller than the Earth, casting a very narrow umbra path).