"Moving Planet" Sun, Earth and Moon System PPT Courseware

Description

"Moving Planet" Sun, Earth and Moon System PPT Courseware

1. Geocentrism

In the second century AD, Ptolemy proposed his own theory of the structure of the universe, namely the "geocentric theory".

Geocentric theory believes that the earth is the center of the universe and is stationary, and that the sun, moon and other planets all move around the earth.

The geocentric theory was not overturned by Copernicus until the 16th century.

The establishment and development of geocentrism

The geocentric theory was first proposed by the ancient Greek scholar Eudoxus, and was gradually established and improved through further development by Aristotle and Ptolemy.

Basic point:

1. The earth is a sphere.

2. The earth is stationary and is at the center of the universe. From the earth outward, there are the moon, Mercury, Venus, the sun, Mars, Jupiter and Saturn, and then outside is the celestial sphere inlaid with all the stars - the stellar sky. The outermost part is the prime mover that drives the motion of celestial bodies.

3. All the sun, moon and stars rotate at a constant speed around the earth.

2. Heliocentric theory

Copernicus proposed the heliocentric theory in the 16th century.

Heliocentric theory holds that the sun is stationary and the earth and other planets move around the sun.

In 1543, Copernicus's "On the Revolutions of the Celestial Spheres" was published, which described the heliocentric theory in detail.

The establishment and development of heliocentric theory

In more than 300 BC, Heraclitus and Aristarchus had mentioned that the sun was the center of the universe and that the earth moved around the sun. The complete heliocentric universe model was proposed by Polish astronomer Copernicus in his "On the Revolutions of the Celestial Spheres" published in 1543.

Basic point:

(1) The sun is stationary, and in the center of the universe, Mercury, Venus, Mars, Jupiter, Saturn, like the earth, all revolve around the sun in circular orbits at a uniform rate.

(2) The moon is a satellite of the earth. It revolves around the earth once a month in a circular orbit centered on the earth, and revolves with the earth around the sun.

(3) The earth rotates once every day, and the sky does not actually rotate. It is only due to the rotation of the earth that we see the sun, moon and stars rising in the east and setting in the west every day.

Kepler's three laws of planetary motion

Kepler's first law: (Law of elliptical orbits)

The orbits of all planets around the sun are ellipses, with the sun at one focus of the ellipse.

Kepler's second law: (area law)

For any planet, the line connecting it to the Sun sweeps out equal areas in equal amounts of time. SAB=SCD=SEK

Kepler's third law: (Periodic law)

The cube of the semi-major axis of the orbit of all planets is proportional to the square of the period of revolution. R3/T2=K

Difficulties Encountered by Geocentric Theory

1. The sun appears larger (and therefore closer) at noon in winter in the Northern Hemisphere than at noon in summer.

2. Mars retrograde.

3. The movement of the sun is slower in summer and slightly faster in winter.

The heliocentric theory successfully solved the difficulties encountered by the geocentric theory

Assume that the movement of the earth around the sun is an elliptical motion, and the sun is at the focus. According to the characteristics of the curved motion, the time from the autumnal equinox to the winter solstice and then to the spring equinox is shorter than the time from the spring equinox to the summer solstice and then to the autumnal equinox. Therefore, autumn and winter are shorter than spring. Summer is shorter.

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Update Time: 2024-11-22

This template belongs to science courseware People's Education Press Sixth Grade Science Volume 1 industry PPT template

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