Which is the largest natural satellite (moon) in our solar system?

Introduction / Context:
The solar system contains many natural satellites, commonly called moons, orbiting different planets. Knowing which moon is the largest helps in understanding comparative planetology and is a favourite topic in astronomy based general knowledge questions. This question asks you to identify the largest natural satellite among well known examples such as Titan, Ganymede, and Earth's Moon.

Given Data / Assumptions:

• We are asked for the largest natural satellite in the solar system by physical size (diameter).
• Options include Titan, Ganymede, Callisto, Earth's Moon, and None of the above.
• We consider recognised major moons of the planets, not dwarf planet satellites.

Concept / Approach:
Several moons in the outer solar system are larger than Earth's Moon. Ganymede, a moon of Jupiter, has the largest diameter, slightly bigger than that of Titan (Saturn's moon) and also larger than Mercury. Titan is the second largest moon, followed by Callisto and Io. Earth's Moon is smaller than both Ganymede and Titan. Therefore, among the given options, Ganymede is the correct answer as the largest natural satellite in the solar system.

Step-by-Step Solution:
Step 1: Recall approximate sizes: Ganymede has a diameter of about 5,268 km, making it the largest moon. Step 2: Titan's diameter is about 5,150 km, placing it very close to but still smaller than Ganymede. Step 3: Callisto has a diameter of around 4,820 km, smaller than both Ganymede and Titan. Step 4: Earth's Moon has a diameter of about 3,474 km, which is clearly smaller than all the above. Step 5: Conclude that Ganymede is the largest natural satellite in the solar system and select that option.

Verification / Alternative check:
Astronomy references and data tables list Ganymede as larger in diameter than the planet Mercury, which is a useful memory aid. Titan, although notable for its thick atmosphere, is slightly smaller in diameter. Earth's Moon, while familiar to us, is not the largest moon overall. None of the recent discoveries of outer system moons have surpassed Ganymede in size. This consistent ranking across scientific sources verifies that Ganymede is indeed the largest natural satellite in our solar system.

Why Other Options Are Wrong:
Titan (moon of Saturn): Second largest moon, slightly smaller in diameter than Ganymede. Callisto (moon of Jupiter): Large but smaller than both Ganymede and Titan. Earth's Moon: Smaller than the three large outer moons listed, especially Ganymede and Titan. None of the above: Incorrect because Ganymede, the correct moon, is explicitly given as an option.

Common Pitfalls:
Some students may think Titan is the largest because it is often emphasised for its atmosphere and surface lakes. Others may assume Earth's Moon is the largest simply because it is the most familiar. To avoid confusion, remember this hierarchy: Ganymede is largest, Titan is second, followed by Callisto and then Io, with Earth's Moon further down the list. This ranking makes the question straightforward once memorised.

Final Answer:
The largest natural satellite in our solar system is Ganymede (moon of Jupiter).