1. The Earth-Moon System Moon Mass 7.3483 x 1022 kg
Equatorial Radius km
Earth
Mass x kg
Mean Radius km

2. Orbital Parameters
Average distance from Earth 384,400 km ( A.U.)
Perigee ,300 km Eccentricity
Orbital Inclination to Ecliptic degrees
Sidereal Orbit Period Earth days
Sidereal Rotation Period Earth days
Equatorial Inclination to Orbit degrees

3. Origin of the Moon
Likely formed after a Mars-sized body collided with Earth
Moon formed out of the debris

4. Phases of the Moon

5. Phases Synodic month 29.53 days Sidereal Lunar Orbit 27.32 days
Actual period variable – perturbations
Moon and Sun both subtend ~0.5 degrees
Eclipses – Lunar, Solar
Occur when moon curs ecliptic, twice a year
Approximately 4 to 7 eclipses per year

6. Total Solar Eclipse 1999

7. Tides in Fundy Bay

8. Different Types of Tides
Semidiurnal
Mixed Tide
Diurnal

9. Tidal Forces

10. What causes tides Main constituent Principal Lunar Semidiurnal
12 hr 25 min period
Slightly longer than 12 hrs due to Lunar orbit – same direction as Earth’s spin
Other effects – Sun’s gravity, inclination of Earth’s spin, moon’s orbit, variation in distances
Coastline

11. Spring and Neap Tides

12. Roche Limit

13. Interacting Galaxies
NGC 4676: When Mice Collide Credit: ACS Science & Engineering Team, NASA

14. Whirlpool Galaxy
NGC Credit NASA/ESA