Question

which of the following is not one of the observed characteristics of our solar system?
all moons orbit planets in a counterclockwise direction
all planets look as though they lie along a flattened circular plane or disk
all planets go in the same circular direction
the sun and planets rotate in the same direction

Explanation:

1. For the solar system, planets lie in a flattened disk (the ecliptic plane), so the option about planets in a flattened plane is a characteristic.
2. Most planets orbit the Sun in the same (counterclockwise) direction, and the Sun and most planets rotate in the same direction (due to the solar nebula theory).
3. However, not all moons orbit planets counterclockwise—some moons (like Triton around Neptune) have retrograde orbits (clockwise relative to the planet's rotation). So the statement "all moons orbit planets in a counterclockwise direction" is not a characteristic.

Answer:

all moons orbit planets in a counterclockwise direction