How to build an active star

Use a piece of 180× 160 (mm 2) white cardboard as the bottom plate of (1) star chart, drill a small hole in its center, and stick a piece of yellow paper with a width of 4 mm at both ends (Figure 19- 1). (2) Cut a cardboard disc with a diameter of 170 mm, drill a small hole at the center of the circle, and connect the disc with the bottom plate with a shoe ring. The connection method is to put the shoe ring in the central hole of the bottom plate, line it with several layers of tissue paper, then put it on the disc, then nail the bent iron piece at the mouth of the shoe ring, and finally tear off the tissue paper lined to leave a gap, so that the disc can rotate flexibly on the bottom plate. Draw the stars on white paper and stick them on the disk. When pasting, make the Polaris in the center of the map coincide with the center of the disk.

(3) Draw a curved surface on 180× 160 (mm 2) white cardboard, and dig diagonal and elliptical holes at the top of the graph with a knife. Before digging an oval hole, check the latitude of the residence on the map. If you live near 30 north latitude, dig along the 30 line; if you live near 40 north latitude, dig along the 40 line. Finally, glue the yellow cardboard and paste the surface map, and the activity map is completed. Both sides of the map disk are exposed 5 mm from the panel, which is convenient for fingers to touch the disk. Use (1) to turn the disc, and align the date line on the star map with the time line on the panel according to the date and time of the stargazing day. (2) Lift the active star map to the top of your head, so that the direction on the star map is consistent with the actual direction. The elliptical circle in the star map represents the surrounding horizon, and the center of the elliptical circle is the zenith; The constellation near the circle is the constellation near the horizon, and the constellation in the center of the circular hole is the constellation above the observer's head. At this time, you can look for bright stars in the sky by comparing the star maps.