Astronomical topics in the first day of junior high school

The light of Polaris is the earth axis, and the direction pointed by the earth axis is the direction of Polaris, perpendicular to the equator. In geography class, there are four special solar terms: vernal equinox, summer solstice, autumn equinox and winter solstice. Knowing the direct latitude of their sun can do this problem. When the included angle α is acute angle, it is summer solstice, when it is right angle, it is spring (autumn) minute, and when it is obtuse angle, it is winter solstice.