1. Phases of the Moon

3. Half of the moon is always illuminated

4. We see all, none, or some of that illumination

7. The same side of the moon always faces the Earth.

9. Time for one rotation (axis) Time for one orbit (Earth) =

10. Half of the moon is always illuminated We see all, none, or some of that illumination

11. Half of the moon is always illuminated We see all, none, or some of that illumination - But it’s not always the same half!

12. p2 =p2 = ________ G(M Earth ) a3a3 4π24π2 p: period (time for Moon to go around Earth) a: Moon-Earth distance Take home #1: If M becomes 0.5M, what is the new value of p? A few notes for the take home... p2 =p2 = ___ M Earth C

13. A few notes for the in-lab...

22. p 2 = a 3 p: period in Earth years for one orbit around the Sun a: distance in AU from the planet to the Sun

23. p2 =p2 = ________ 4π24π2 G(M 1 +M 2 ) a3a3 G = gravitational constant = 6.67 x 10 -11 m 3 /kg/s 2 M Sun = 1.99 x 10 30 kg M Planet << M Sun p2 =p2 = ________ G(M Sun ) a3a3 4π24π2 ________ G(M Sun ) 4π24π2 = 1 seconds  years meters  AU

24. F = _______ GM 1 M 2 d2d2 M 1 = Earth’s mass M 2 = Moon’s mass d = distance between Earth and Moon F = force that the Moon feels as it orbits the Earth If d stays the same, what happens to F if Earth’s mass decreases?

25. p2 =p2 = ________ 4π24π2 G(M 1 +M 2 ) a3a3 G = gravitational constant = 1.475 x 10 -34 AU 3 /kg/day 2 M Earth = 5.97 x 10 24 kg M Moon = 7.36 x 10 22 kg p = period in days of the Moon’s orbit around Earth a = distance in AU between Moon and Earth 400,000km x _____________ 1 AU 150,000,000km =.002667 AU a =