6、scientific and educational instruments:Three-ball instrumentDue to the earth's ten kinds of inclined body revolution and rotation, the northern hemisphere has short days and long nights in winter and short days and short nights in summer. The Southern Hemisphere is the opposite.

7. The moon is full and short: the moon itself does not emit light. All the moon we can see is illuminated by the sun. Like the earth, it is always half illuminated by the sun at any time (except during lunar eclipses), because it is constantly orbiting the earth. Sometimes the illuminated part is all facing us and sometimes all behind us, thus causing a change of full and short of profits and losses. Astronomically, it is called "moon phase alternation".

To do this experiment, first turn on the power supply and let the moon detour between the sun and the earth. the backlight side of the moon faces the earth. at this time, the moon phase is called "Shuo" (equivalent to the first place in the lunar calendar). Continue to let the moon turn to the middle position of "Shuo" and "upper string", and the sun gradually
Gradually illuminate its part towards the edge of the earth's hemisphere, you can see the upper chord, look down the chord, then you can see the west of the upper chord meniscus one after another, the lunar half is the full moon, the lunar 22nd and 3rd morning can see the half moon alternating in the east.

8. Scientific and educational instruments: solar eclipse and lunar eclipse of the three-sphere instrument: when the moon moves between the sun and the earth and is in a straight line, a "solar eclipse" will occur. Its occurrence time is basically at the beginning of the lunar month (that is, the new moon); If the earth moves between the sun and the moon and is in a straight line, a "lunar eclipse" will occur. The time must be in the lunar calendar (namely)

9.24 solar terms: the earth revolves around the sun. every 15 degrees from the equinox is a solar term, and a 360 degrees per week is 24 solar terms. Reflecting the great pioneering work of our working people in mastering the laws of nature and carrying out agricultural production.

10. Scientific and educational instruments: fromThree-ball instrumentThe following can be seen on the Earth model:

A, national date line;
B, the equator, the Tropic of Capitalism, the location of the South Arctic Circle;
C. Position of the five belts;
D. The location of seven continents and four oceans.