The tilt of Uranus's axis was first deduced from observed orbital motions of its moons. For the deduction of this tilt to be correct, it was necessary to assume that the moons:
A)moved in the ecliptic plane, or at least in the plane of the orbit of Uranus.
B)passed over both north and south poles of the planet, thereby indicating the planet's spin axis.
C)were not affected by the gravitational field of the Sun, which would force their orbits to deviate from the planet's equatorial plane.
D)were orbiting in the equatorial plane of Uranus.

Question

Quizplus · Accepted Answer

The deduction was based on the assumption that the moons were orbiting in the equatorial plane of Uranus, which could only be the case if Uranus's spin axis was tilted relative to its orbit.

The Tilt of Uranus's Axis Was First Deduced from Observed