The phrase "a chip off the old block" apparently also applies to the outer moons of our solar system.
A tiny moon whirling around Neptune that was uncovered in Hubble Space Telescope photographs taken in 2013 has puzzled astronomers ever since then because it is very close to a much larger moon named Proteus. The orbits of the two moons are presently 7,500 miles apart.
Proteus, at 260 miles in diameter, is roughly the size of the state of Ohio. By contrast, Hippocamp is just 20 miles across, or the size of metropolitan Columbus, Ohio. Proteus should have gravitationally swept aside or swallowed... Read more