Orbit and Rotation of Mercury

Mercury has a rather unusual motion:

• orbit radius ~ 0.4 R_Earth
• distance from sun ~ 0.4 AU, but quite eccentric
  • min distance = 0.31 AU
  • max distance = 0.47 AU
• orbit period: ~90 days
• rotation period: ~60 days
• The rotation period is (almost) exactly 2/3 of the orbit period.
  
• This is an example of tidal effect.
• Recall that for the Moon, the rotation period is 1.00 times the orbit period.

What would you see if you wore your purple clothes and stood on Mercury?
Think it through, with a picture.
The rotation is 1.5 times as fast as the orbital revolution.

We see that after one Mercury year, the time of day has gone from noon to midnight!