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 and sun spots.
Early Chinese Star Chart

4. ANCIENT ASTRONOMY
Dresden Codex
The Mayan culture was able to accurately predict solar and lunar eclipses.
Aztec Calendar
The Mayans also developed a very accurate calendar, later adopted by the Aztecs.
The Caracol
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. LUNAR ECLIPSE

8. Lunar Eclipse February 20, 2008

9. 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 pi
Radius = 6370 km

10. FLASHCARD
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) km
B) 15,278 km
C) 24,000 km
D) 48,000 km

11. 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)

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. 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

14. 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

15. 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

16. 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)