Which pair of planets in the solar system has no natural satellites or moons?

Introduction / Context:
Most planets in the solar system have one or more natural satellites, commonly called moons. However, a few do not have any moons at all. Knowing which planets lack natural satellites is a basic astronomy fact that often appears in school level science and general knowledge exams.

Given Data / Assumptions:

• The question asks for a pair of planets that have no moons.

• Options list pairs of inner and outer planets.

• Observational astronomy has identified moons around all giant planets and around Mars and Earth.

• Only the innermost rocky planets are known to have no natural satellites.

Concept / Approach:
The key concept is to remember which planets have known moons. Earth has one moon, Mars has two small moons, and all four gas giants Jupiter, Saturn, Uranus, and Neptune have many moons. In contrast, Mercury and Venus are the only planets without any confirmed natural satellites. This pattern remains a standard fact in introductory solar system studies.

Step-by-Step Solution:
Step 1: List the inner planets: Mercury, Venus, Earth, and Mars. Step 2: Recall that Earth has one large moon. Step 3: Remember that Mars has two small moons named Phobos and Deimos. Step 4: Note that Mercury and Venus are not known to have any natural satellites. Step 5: Therefore select Mercury and Venus as the pair with no moons.

Verification / Alternative check:
Solar system charts and space agency educational material clearly indicate the number of known moons around each planet. They show multiple moons for the gas giants and at least one for Earth and Mars, while listing zero for Mercury and Venus. This consistent information across credible sources confirms that only Mercury and Venus form the correct pair in this question.

Why Other Options Are Wrong:

• Earth and Mars both have natural satellites, so they cannot be the correct pair.

• Jupiter and Saturn are gas giants with many moons each, including large ones like Ganymede and Titan.

• Uranus and Neptune also have multiple moons and are not without satellites.

Common Pitfalls:
Some students may mistakenly think that Mars has no moons because its satellites are small, or they may forget about the many moons of outer planets. To avoid confusion, it is helpful to memorise a quick rule that all planets except Mercury and Venus have at least one moon, and gas giants have many.

Final Answer:
The planets with no natural satellites are Mercury and Venus.