4 ms·
Mars (mean diameter 6780 km) has two known moons, Diamos (mean diameter of 12.4 km) and Phobos (mean diameter of 22 km). So Phobos is ~0.3% the diameter of mars
by Chris2048 6y ago
Mars (mean diameter 6780 km) has two known moons, Diamos (mean diameter of 12.4 km) and Phobos (mean diameter of 22 km). So Phobos is ~0.3% the diameter of mars, and Diamos is ~0.2%; for comparison the moon is 27% the diameter of Earth, though is considered abnormally large. Also, "Mars may have moons smaller than 50 to 100 metres".
I'm surprised there's no lower limit on what is considered a moon. Wikipedia suggests smaller objects are called "moonlets", but I guess Russell's teapot would count as one, but for the uncertain fact it might not be considered "natural"?
- lizknope 6y agoWe have changed the definition of "planet" multiple times so I'm sure we will redefine "moon" as well. Pluto was recently demoted but this has happened before to Ceres and others. https://en.wikipedia.org/wiki/IAU_definition_of_planet https://en.wikipedia.org/wiki/IAU_definition_of_planet By 1851, the number of "planets" had grown to 23 (the eight recognised today, plus fifteen between Mars and Jupiter), and it was clear that hundreds more would eventually be discovered. Astronomers began cataloguing them separately and began calling them "asteroids" instead of "planets"