Final answer:
The incorrect characteristic of our planetary system is the assertion that most planets are about the same physical size option (d), which is not true, as planets range considerably in size from Mercury to the gas giants.
Step-by-step explanation:
The characteristic of our planetary system that is NOT typical is (D) The physical size of most of the planets is about the same. This statement is incorrect because the sizes of the planets in our solar system vary greatly, from the smallest terrestrial planet, Mercury, to the gas giants like Jupiter and Saturn which are many times larger. On the other hand:
- (A) The spin axes of most of the planets are indeed aligned to within 30° to the perpendicular of the orbital plane, with some notable exceptions like Uranus, which has an axial tilt of approximately 98°.
- (B) The orbits of most planets are almost circular, with slight elliptical shapes known as low eccentricity.
- (C) Most of the planets orbit the Sun in the same direction, which is counterclockwise when viewed from above the Sun's north pole.