Q4_Week_Astronomical Observations Before the Advent of Telescopes.pptx

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1. PHYSICAL SCIENCE SEMESTER 2- 4th grading

2. Astronomical Observations Before the Advent of Telecopes

3. Observations Rising and setting of the Sun in the east and west respectively Point where the sun rises and sets in the horizon varies in a year - earth’s elliptical orbit - earths angle of tilt

4. Observations Phases of the moon

5. Observations Eclipses – when when one celestial body such as a moon or planet moves into the shadow of another celestial body

6. Observations Daily and Annual Motion of the Stars - Diurnal Motion - refers to the apparent movement of stars and other celestial bodies around Earth. Annual Motion - apparent yearly movement of the stars as observed from Earth as a direct effect of the Earth’s revolution around the sun.

7. Observations Planets discovered before telescopes were invented - Mercury, Venus, Mars, Jupiter, Saturn

8. Key Concept Around 500 B.C., most Greeks believed that the Earth was round, not flat. It was Pythagoras and his pupils who were first to propose a spherical Earth. shadows that the Earth cast on the Moon during a lunar eclipse is circular In 340 BC Aristotle Aristotle listed several arguments for a spherical Earth which included the positions of the North Star, the shape of the Moon and the Sun, and the disappearance of the ships when they sail over the horizon.

9. ERATOSTHENES – gave the most accurate size during their time Syene (Southern Egypt): a vertical object did not cast any shadow at noontime during the summer solstice; Alexandria: vertical object still casts a shadow computed the circumference of the Earth to be approximately 250 000 stadia (a stadium is a unit of measurement used to describe the size of a typical stadium at the time), about 40 000 kilometers. SIZE OF THE SPHERICAL EARTH

10. SIZE OF THE SPHERICAL EARTH ERATOSTHENES

11. ANAXAGORAS - Anaxagoras was able to explain what causes the phases of the moon. According to him, the moon shone only by reflected sunlight. Since it is a sphere, only half of it illuminated at a time. This illuminated part that is visible from the earth changes periodically. ANAXAGORAS

12. EUDOXUS - Eudoxus proposed a system of fixed spheres. He believed that the Sun, the moon, the five known planets and the stars were attached to these spheres which carried the heavenly bodies while they revolved around the stationary Earth. EUDOXUS

13. ARISTOTLE - the earth is spherical in shape since it always casts a curved shadow when it eclipses the moon. He also believed that the earth was the center of the universe. The planets and stars were concentric, crystalline spheres centered on the earth. ARISTOTLE

14. ARISTARCHUS -the very first Greek to profess the heliocentric view. helios means sun; centric means centered. ARISTARCHUS

15. HIPPARCHUS -observed and compared the brightness of 850 stars and arranged them into order of brightness or magnitude HIPPARCHUS

16. CLAUDIUS PTOLEMY - the earth was the center of the universe. His Ptolemic Model claimed that the planets moved in a complicated system of circles. This geocentric model also became known as the Ptolemic System CLADIUS PTOLEMY

17. CLADIUS PTOLEMY