Introduce the time when an annular solar eclipse occurs every few years.

2. Annular eclipse is also related to the earth and the moon itself. Because the earth and the moon are opaque spheres, the sun shines and is sometimes blocked by the moon. An annular eclipse may occur on the first and second day of the lunar calendar.

In the above days, if the earth, the moon and the sun are on the same straight line, an annular eclipse will occur. The light from the sun is blocked by the moon. In the shadow area of the moon, people can't receive the sun, so they can't see it. Moreover, because the distance between the moon and the earth is different from that between the moon and the sun, and the distance between the moon and the sun is much greater than that between the moon and the earth, the moon covers the sun and only exposes a part around it, thus forming an annular eclipse.