GENERAL KNOWLEDGE

Detailed explanation-1: -Of the terrestrial (rocky) planets of the inner solar system, neither Mercury nor Venus have any moons at all, Earth has one and Mars has its two small moons. In the outer solar system, the gas giants Jupiter and Saturn and the ice giants Uranus and Neptune have dozens of moons.

Detailed explanation-2: -You may have guessed the answer in the first case. Mercury is just too close to the sun, and that is all there is to it. Any Moon that Mercury might have had or tried to capture would be in an unstable orbit because the sun would tug at it.

Detailed explanation-3: -Lassell spotted Triton on Oct. 10, 1846 – just 17 days after a Berlin observatory discovered Neptune. Scientists using powerful telescopes and spacecraft have since discovered a total of 14 moons orbiting the distant world.

Detailed explanation-4: -Mercury and Venus are referred to as inferior planets, not because they are any less important, but because their orbits are closer to the sun than is Earth’s orbit. They always appear close to the sun in Earth’s morning or evening sky; their apparent angle from the sun is called elongation.