What causes Mercury's 3:2 spin-orbit resonance?
A) the planet's closeness to the Sun
B) the planet's very eccentric orbit
C) the planet's high density
D) tidal torques operating on the planet
E) All of the above are factors.
Question 2
Into how many constellations is the celestial sphere divided?
A) 12
B) 44
C) 57
D) 88
E) 110