1. Advances in contemporary physics and astronomy --- our current understanding of the Universe Lecture 7: Physics of our star, the Sun May 21 th, 2003

2. Eratosthenes and the size of the Earth Eratosthenes 276 –194 BC Radius of the Earth ~ 6,300 kilometers

3. Hipparchus and the distance to the Moon Hippaarchus (190-120 BC) the Moon was 59 times the radius of the Earth.

4. Aristarchus and the distance to the Sun Aristarchus of Samos Born: about 310 BC in Greece Died: about 230 BC in Greece Aristarchus was trying to calculate the distance between the Earth and the Sun by calculating angle of Sun-Earth-Moon when it is Half Moon. His angle, 87º is about 1.5º off the real value, 88.5º. His estimation is about 20 times smaller.

5. Solar system

6. Space exploration

7. References http://spaceboy.nasda.go.jp/