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ANCIENT ASTRONOMY

ANCIENT ASTRONOMY. Chapter 1. ANCIENT ASTRONOMY. In the British Isles, stones were used to keep track of the Sun and Moon. Stonehenge. ANCIENT ASTRONOMY. The Chinese developed a working calendar and kept careful track of comets, eclipses sun spots and variable objects.

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ANCIENT ASTRONOMY

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  1. ANCIENT ASTRONOMY Chapter 1

  2. ANCIENT ASTRONOMY • In the British Isles, stones were used to keep track of the Sun and Moon. Stonehenge

  3. ANCIENT ASTRONOMY • The Chinese developed a working calendar and kept careful track of comets, eclipses sun spots and variable objects Early Chinese Star Chart

  4. Dresden Codex Aztec Calendar The Caracol ANCIENT ASTRONOMY • The Mayan culture was able to accurately predict solar and lunar eclipses. • The Mayans also developed a very accurate calendar, later adopted by the Aztecs. • This structure, called the Caracol, at Chitzen Itza may have been used as a Venus Observatory

  5. EARLY GREEK ASTRONOMY • Shape of Earth (circa 400 BC)

  6. LUNAR ECLIPSE GEOMETRY

  7. LIGHT RAYS FROM THE SUN

  8. LUNAR ECLIPSE

  9. Shape Earth: Erastothenes’ Method

  10. EARLY GREEK ASTRONOMY • Shape of Earth (circa 400 BC) • Size of Earth (Erastothenes circa 200 BC) • 7/360 = AS/Circumference • AS = (5000 Stadia) 800 km • Circumference = 40,000 km • Knowing p • Radius = 6370 km

  11. SUPPOSE THAT ERASTOTHENES HAD MEASURED THAT THE SUN WAS OVERHEAD AT SYENE AND 9 DEGREES AWAY FROM OVERHEAD AT ALEXANDRIA. WHAT WOULD HE HAVE CONCLUDED FOR THE RADIUS OF EARTH IF THE SYENE-ALEXANDRIA DISTANCE WAS 1200 KM? A)7639 km B) 15,278 km C) 24,000 km D) 48,000 km FLASHCARD

  12. EARLY GREEK ASTRONOMY • Shape of Earth (circa 400 BC) • Size of Earth (Erastothenes circa 200 BC) • Relative Size of Earth and the Moon (Aristarchus circa 280 BC) • From lunar eclipse ~1/3

  13. LIGHT RAYS from the SUN

  14. LUNAR ECLIPSE

  15. EARLY GREEK ASTRONOMY • Shape of Earth (circa 400 BC) • Size of Earth (Erastothenes circa 200 BC) • Relative Size of Earth and the Moon (Aristarchus circa 280 BC) • Size of the Moon, Distance to the Moon • Radius = 1730 km (0.27 Earth) • Distance = 380,000 km – from size and angular size

  16. EARLY GREEK ASTRONOMY • Shape of Earth (circa 400 BC) • Size of Earth (Erastothenes circa 200 BC) • Relative Size of Earth and the Moon (Aristarchus circa 280 BC) • Size of the Moon, Distance to the Moon • Distance to the Sun

  17. EARLY GREEK ASTRONOMY • Angular size Sun, Moon did not change (circular) • cos X = Dmoon/Dsun • Dmoon already known – measure X - failed • X close to 90o – if 90 Sun infinitely far away • Modern X = 89o 51’ Sun 380 times farther than Moon X

  18. HELIOCENTRIC SOLAR SYSTEM • Greek Argument that the Sun is at the Centre of the Solar System • Sun is much farther from Earth than the Moon (380 times farther) • Since the Sun and Moon have the same angular size, Sun is 380 times larger than Moon • Earth is 3 times larger than the Moon, thus the Sun is 100 times larger than Earth • Thus, the Sun is much more massive than Earth (assumes both have about the same density) • Hence, the Greeks concluded the the Sun is at the centre of the system (circa 200 BC)

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