scientific and educational instruments:Three-ball instrumentIs to absorb the length of similar products, carefully designed and developed. Experiments show that it has the characteristics of accurate and stable operation, simple and flexible operation, beautiful and novel structure, firm and durable.

scientific and educational instruments:Three-ball instrumentDemo

1. Rotation and revolution of the earth: when the earth keeps rotating from west to east around its own axis, it also rotates around the sun on one side. The former is rotation, the latter is revolution. Rotation one week and one day and night; One week of revolution is a year (365-1/4 days, the angle and direction of the earth's axis tilt are always the same.)

2. Moon revolution: While demonstrating the rotation and revolution of the earth, the moon can be observed to orbit the earth in a counterclockwise direction, and it also revolves around the sun with the earth (one revolution is a lunar month)

3. Day and night in the same place: when the cursor turns from darkness to light, that is, "morning", it is facing the sun as "noon", leaving the sun and turning to darkness is "dusk", and this period of time is "day"; When the cursor enters darkness, it is night.

4. Day and night at the same time: When the earth rotates, the place facing the sun at the same time is daytime, the place carrying the sun is night, and some places are morning or dusk. The North and South Poles are half-year days or nights except before and after the vernal equinox and the autumnal equinox.

5. The changes of the four seasons and cold and heat in the three globes: for the northern hemisphere, the sun shines directly on the Tropic of support during the summer solstice, and there are many light parts and few backlight parts, so the days are long and the nights are short, and the climate is hot. During the winter solstice, the sun obliquely shines on the Tropic of support, and there are few light parts and many backlight parts, so the days and nights are cold climate. The Southern Hemisphere is the opposite. During the vernal equinox and the autumnal equinox, sunlight shines directly on the equator, and the northern and southern hemispheres have similar lighting conditions, borderline between winter and summer, so day and night are equally divided, and the climate is mild.