Topic 3- The Earth, Moon, Sun System

Eratosthenes

• He measured shadows in Syrene and Alexandria and calculated the angle between them (7.12⁰)
• He the measured the distance between the 2 cities (5000 stadia)
• He then calculated the circumference

Aristarchus

• Measured witdth of Moon and Sun using lunar eclipse (2⁰)
• He then triangulated the Moon, Sun and Earth
• He then measured the angle between the half Moon and Sun (87⁰)
• Worked out the Sun was 18-20 times further away

Tides

• Tides are caused by the gravitational attraction of the Moon and Sun pulling on the water on Earth's surface
• Tides change because the Moon is orbiting Earth, so the gravitaional pull is stronger in some places compared to others
• Tides also change because the Sun exerts a tidal force that is 40% that of the Moon, meaning it is stronger when in line with the Sun and Moon

Spring and Neap Tides

• Spring tides…