Find the odd man out

In a "find the odd one out" classification question, three of the four given items share a common category or defining property, while exactly one item belongs to a different category. Solving it means identifying the shared property among the majority and checking which single item does not fit that property.

Here, Earth, Mars, and Jupiter are all planets of the solar system — each follows its own primary orbit directly around the Sun. The Moon, however, is not a planet; it is a natural satellite whose primary orbit is around Earth, even though the Earth-Moon system as a whole also moves around the Sun.

• Earth — a planet of the solar system, orbiting the Sun directly.

• Mars — a planet of the solar system, orbiting the Sun directly.

• Jupiter — a planet of the solar system, orbiting the Sun directly.

• Moon — not a planet; a natural satellite whose primary orbit is around Earth, not an independent orbit around the Sun.

Since three items share the "planet" category and only the Moon does not, the Moon is the odd one out among the four.