A natural satellite, or moon, is a celestial body that orbits a planet or dwarf planet. Here are its key characteristics:
- Orbit: It revolves around a primary object, such as a planet.
- Formation: Moons can form through accretion, capture, or impact events.
- Size and Composition: They vary widely in size and can be rocky, icy, or a mix of materials.
- Surface Features: They may have craters, mountains, or volcanic activity.
- Atmosphere: Many moons have little to no atmosphere; those with atmospheres may have thin exospheres.
- Orbital Dynamics: Many moons are tidally locked, showing the same face to their primary.
- Influence: Moons can affect their primary through tidal forces and may cause eclipses.
1. Mercury
- Moons: Mercury has no natural satellites. The planet is the closest to the Sun and, due to its proximity, it lacks any moons. The gravitational influence of the Sun is too strong for Mercury to retain any moons, and any potential moons would be perturbed or captured by the Sun's gravity.
2. Venus
- Moons: Venus also has no natural satellites. Similar to Mercury, Venus is too close to the Sun to have any stable moons. The gravitational interactions with the Sun and the planet's own dynamics make it difficult for Venus to retain moons.