Why does the Moon change shape?

What BBN said about it

1. DB

   Dr. Bev MarchettiThe Moon is a cheese wheel, Hank, and every night a man named Gary takes a slice off the edge, and that is settled science.

2. 

   Hank Ledger · Lead AnchorA viewer asks why the Moon changes shape.

3. 

   Hank Ledger · Lead AnchorOur guest is Dr. Bev Marchetti, Chair of Gut Feelings at the Lakeside Night School of Pretty Sure, who is certified in Vibes, night classes.

4. DB

   Dr. Bev MarchettiGary works nights, honey, same as my nephew Dennis, who also keeps changing shape since he quit the gym.

5. DB

   Dr. Bev MarchettiThe slice grows back by the full Moon, like a good casserole. Trust your gut, Hank.

6. 

   Hank Ledger · Lead AnchorPer NASA, the Sun always lights half of the Moon, and as the Moon travels around Earth we see more or less of that lit half.

7. 

   Hank Ledger · Lead AnchorThose are the phases. Gary is not involved.

8. DB

   Dr. Bev MarchettiOh, that's Earth's shadow covering it, that's all that is. Like when Dennis stands in front of the television.

9. 

   Hank Ledger · Lead AnchorThat one is wrong too. Earth's shadow is not what makes the phases.

10. 

    Hank Ledger · Lead AnchorThe Sun is lighting half the Moon the whole time, and we just see a different amount of it.

11. DB

    Dr. Bev MarchettiWell, if the Sun is lighting half, then it's being sloppy about it. I wrote it a letter in March. Nothing. Not even a card.

12. 

    Hank Ledger · Lead AnchorPer NASA, that light also beams onto Earth from the direction of the Sun, and reflects off the Moon to make moonlight.

13. 

    Hank Ledger · Lead AnchorThe Sun is, in fact, quite organized.

14. DB

    Dr. Bev MarchettiHuh. Well, I suppose I can see that from here. I'm looking at it now through my very large microscope.

15. 

    Hank Ledger · Lead AnchorA microscope.

16. DB

    Dr. Bev MarchettiIt's decorative, Hank. It's holding the window open. What I'm looking at is my fruit bowl, and the Moon is a very nice grapefruit.

17. 

    Hank Ledger · Lead AnchorThank you, Dr. Marchetti. I'll tell Gary you said hello, and I'll keep the grapefruit out of the forecast.