Classification – Odd one out (planet with known life): Which planet is unlike the others: Jupiter, Uranus, Mercury, Earth?

Introduction / Context:
Astronomy classification questions often rely on broad, uncontested properties. The most decisive distinction here is the presence of known life. Among the listed planets, only Earth is confirmed to harbor life, making it a unique outlier compared to gas/ice giants and airless inner worlds.

Given Data / Assumptions:

• Earth: only planet confirmed to support life as we know it.
• Jupiter: gas giant; hostile atmospheric conditions, no known life.
• Uranus: ice giant; extreme conditions, no known life.
• Mercury: rocky, near-Sun; extreme temperature swings, no known life.

Concept / Approach:
Pick a categorical attribute that creates a single-member class. “Known life” is definitive and produces a one-of-a-kind outlier.

Step-by-Step Solution:
Check life status: Earth → known life; others → none known.Alternative groupings (composition, distance) do not yield a single unique member among these four.

Verification / Alternative check:
One could try “terrestrial vs giant,” but Earth and Mercury would both be terrestrial, failing uniqueness. The “life present” criterion is uniquely decisive.

Why Other Options Are Wrong:

• Jupiter, Uranus, Mercury: no confirmed life; they do not share Earth’s biosignature status.

Common Pitfalls:
Choosing composition or orbital position, which does not isolate a single option here.

Final Answer:
Earth