which planet is 5.5 of earth's mass and has no moon
List of natural satellites Mercury, the smallest and innermost planet, has no moons, or at least none that can be detected to a diameter of 1.6 km (1.0 mi).[1] For a very short time in 1974, Mercury was thought to have a moon.
Mercury (planet) Mercury is the smallest and innermost planet in the Solar System. Its orbital period around the Sun of 88 days is the shortest of all the planets in the Solar System. It is named after the Roman deity Mercury, the messenger to the gods.