Explaining How the Greeks Knew the Earth is Spherical PDF

Explaining How the Greeks Knew that the Earth is spherical It was once believed that the Earth is flat -that there is that place called the "edge of the world" and when you reach it, you will fall. Pythagoras of Samos (572-495 BC) Influenced by Thales and Anaximander Sphere is the most...

Explaining How the Greeks Knew that the Earth is spherical It was once believed that the Earth is flat -that there is that place called the "edge of the world" and when you reach it, you will fall. Pythagoras of Samos (572-495 BC) Influenced by Thales and Anaximander Sphere is the most perfect shape Earth is at the center of the universe Plato (427-347 BC) "My conviction is that the Earth is a round body in the centre of the heavens, and therefore has no need of air or of any similar force to be a support" -Plato no more justification Aristotle (384-322 BC) Earth is spherical. There are stars that were seen in Egypt and Cyprus that is not visible in the northern region. Aristotle (384-322 BC) He further illustrated that when a ship reaches the horizon, the ship will disappear in the observer's sight. Portions of the Earth tend to converge at the center forming a sphere Changing position of stars and constellations as one travels to north or south. Earth's shadow on the Moon during a lunar eclipse is round Eratosthenes of Cyrene (276-194 BC) Famous for calculating the earth's circumference with remarkable accuracy. Eratosthenes of Cyrene (276-194 BC) Conducted an experiment to measure the length of the shadow casted by a vertical stick during the solstice noon in order to figure out the angle the sun made with the vertical direction at Alexandria.  5000 STADIA = 800 KM DISTANCE FROM ALEXANDRIA TO SYENE = 5000 STADIA  7.2 °= 800 km 360 ° = ? Km 360° x800 km = 7.2° 40, 000 km Eratosthenes : Earth’s circumference = 250 000 stadia  The earth was once believed to be flat until the study of the following Greeks: Pythagoras and Plato Earth is spherical Sphere is the most perfect shape  The earth was once believed to be flat until the study of the following Greeks: Aristotle Earth is spherical Considered the position of the stars and the shadow of the Earth formed during eclipse  The earth was once believed to be flat until the study of the following Greeks: Eratosthenes Earth is curved Measured the angle of the sun made with vertical direction Calculated the circumference of Earth. OBLATE SPHEROID It is the shape of the Earth and has bulging equator and squeezed poles.  Comparing and Contrasting Models/Descriptions of the Universe by Eudoxus, Aristotle, Aristarchus, Ptolemy and Copernicus Eudoxus Model Eudoxus Model Earth is fixed at the center of the universe First geocentric model Sphere within spheres (homocentric spheres); System of 27 spheres ❑ 1 for the fixed stars ❑ 3 each for the sun and moon ❑ 4 each for the five planets Aristotle Model Aristotle's Model Earth is fixed at the center of the universe. 55 concentric spheres centered on the Earth rotating at different velocities Aristotle's Model Sun, moon, stars, and other planets have their own spheres Stars were on the outermost sphere Aristarchus's Model Aristarchus's Model First heliocentric model of the universe All planets revolve around the sun along circular paths Moon receives light from the sun Aristarchus's Model Sun is 300 times larger than the Earth Stars - distant suns Moon is closer to Earth than the sun and is orbiting the Earth Ptolemaic's Model Ptolemaic's Model Earth is the center of the entire universe Ptolemaic's Model Each planet is moving in a small circle called an epicycle which is moving around a larger circle called deferent Ptolemaic's Model Stars are moving around another spheres outside the epicycle Copernican Model Copernican Model Sun is the center of the solar universe All celestial bodies revolve around the sun Copernican Model Sun is the closest star to Earth Copernican Model Earth is the third planet from the sun Earth rotates during its revolution around the sun Copernican Model Moon orbits the Earth, stars do not Stars are immovable and very far from the Earth Copernican Model Earth's rotation on its axis causes the diurnal motion of the stars and planets Earth's revolution around the sun causes the annual motion of the sun Thank you! PROJECT : SUNDIAL DEADLINE: NOVEMBER ___, 2024 3 MEMBERS EACH GROUP MUST BE: STURDY CREATIVE DESIGN WITH DOCUMENTATION Instructions to follow: 1. Start this activity just before noon on a sunny day. 2. Take your pencil and poke a hole through the center of the plate. 3. Write the number "12" at the top of the plate with a crayon. 4. Draw a straight line from the number 12 to the center of the plate. 5. Once it's noon, take the plate and straw outside, and place the plate on the ground and poke the straw through the center. 6. Now turn the plate so the shadow of the straw runs along the line to the number 12. 7. Fasten the plate on the ground with some push pins, and check back the sundial an hour later. Where do you think the shadow will be positioned?