Physical Science SHS 14.1~2 The Spherical Earth.pptx

Presentation on Physical Science

1. Lesson 14.1~2 The Spherical Earth

2. explain early beliefs on the shape of the earth; and discuss the development on the idea about Earth’s shape. 1 At the end of the lesson, you should be able to: 2

3. It is an old belief model that the earth is plane or discoidal in form. Early Egyptian, Mesopotamian, and Homer (Greek philosopher) believed that the world is a disk in the ocean. Flat Earth Model Flat Earth Model

4. Israelites thought that the earth is like a disc floating in water where an arched bowl separates the earth from the heavens. They believed that the sky is a solid dome with the sun, Moon, and other planetary objects embedded in it. Flat Earth Model The flat earth model according to the Hebrews.

5. Pythagoras introduced the idea of the round model of the earth in the 6th century BC. Anaxagoras (430 BCE) observed that during lunar eclipse, the earth’s circular shadow was reflected on the moon’s surface. History of the Spherical Earth Model Pythagoras in an old Greek coin.

6. Around 340 BCE, Aristotle listed several arguments for a spherical Earth: Earth was also spherical since the moon and the sun were both spherical The North Star is closer to the horizon for places nearer the equator When the ship sailed, the hull disappeared first, which implied that the surface of the earth was curved. History of the Spherical Earth Model

7. The sinking ship evidence.

8. Around 240 BCE, Eratosthenes attempted to measure the circumference of the earth. In Syene in Southern Egypt, a vertical object did not cast any shadow during the summer solstice, which was not the case in Alexandria. He determined the angle that the sun rays made with the vertical direction by measuring the shadow a vertical stick cast. History of the Spherical Earth Model

9. In Alexandria, the sun rays make an angle of 7.2° from the vertical, whereas, in Syene, it makes an angle of 0 °. He hypothesized that the light rays coming from the sun were parallel, and the earth was curved. He computed the circumference of the earth to be approximately 250 000 stadia or 46 250 km (1 stadia - 185 m). History of the Spherical Earth Model

10. Earth’s circumference based to Eratosthenes calculation.

11. Satellite photos show that the earth is plainly spherical. Astronauts in satellites orbiting in low Earth orbit personally observed curvature of the planet. Modern Evidence Supporting Spherical Earth Model Spacecraft Photos Enhanced satellite photo of the earth.

12. During a lunar eclipse, the shadow of the earth formed on the one side of the moon shows a dark circle. The shape that casts in the moon at which direction is it pointed shows spherical shape. Modern Evidence Supporting Spherical Earth Model Lunar Eclipse Round shadow of the earth cast on the moon during a lunar eclipse.

13. The time difference in different places in the world is due to the presence of a time zone. It can only be explained if the world is round and continuously rotating on its axis. Modern Evidence Supporting Spherical Earth Model Time Zones Rotation of the earth on its axis that forms the time zone.

14. Airplanes are capable of traveling in a straight line without falling off any edges even for a period of time and it can circle the earth without stopping. The curvature of Earth on the horizon is noticeable if you travel in transatlantic flight. Modern Evidence Supporting Spherical Earth Model Riding a Plane An airplane traveling on the curvature of the earth.

15. Early Egyptian and Mesopotamian believed that the world is a disk in the ocean. Homer​, a Greek philosopher in the 8th century BC. According to this belief, the body of water surrounds the circular flat Earth. 1 2

16. Israelites thought that the earth is like a disc floating on water where an arched bowl separates the earth from the heavens. They believed that the sky is a solid dome with the sun, Moon, and other planetary objects embedded in it. Pythagoras at 6th century BC, introduced the idea of the round model of Earth. 3 4

17. Around 340 BCE, Aristotle listed several arguments for a spherical Earth, which included the shape of the moon and the sun, the positions of the North Star, and the disappearance of the ships when they sailed over the horizon. Eratosthenes attempted to measure the circumference of the earth. He computed the circumference of the earth to be approximately 250 000 stadia or 46 250 km ​(1 stadia = 185 m). 5 6

18. Explain how the following evidence prove that the Earth is round and spherical in shape. Evidence Explanation Lunar eclipse Time zone Photos from spacecraft Sinking ship in the horizon Traveling via airplane

19. What do you think will be the most prominent problem in traveling if the earth if flat? Based on the discussion, how did Aristotle proved that the world is round?