Neptunian Moons Trivia Quiz

Answer: Triton

With a diameter of 2 700 km, Triton dwarfs the Neptunian moon with the next-largest diameter, Proteus - Proteus's diameter is a mere fraction of Triton's, at 420 km. Triton is, in fact, the seventh-largest moon in the Solar System.

Answer: 4

The irregular moons Sao, Neso, Laomedeia and Halimede were discovered in 2002 by Matthew J. Holman and his team, consisting of astronomers such as Dan Milisavljevic and John J. Kavelaars. These are all very small moons relatively far away from Neptune following highly eccentric orbits. Triton, Nereid and Larissa - the first three moons to be discovered - were discovered in 1846 (by William Lassell), 1949 (by Gerard Kuiper) and 1981 (by David Tholen and his team of astronomers), respectively.

Answer: Nereid

Nereid was discovered by Kuiper in 1949, and was the second moon of Neptune to be discovered. Nereid is an irregular moon of Neptune which follows a very eccentric orbit in a prograde (clockwise) manner. It is the third largest moon of Neptune, with a diameter of approximately 350 km.

Answer: Neso

Neso takes around 9 741 days to complete a full orbit of Neptune, or around 26.7 years. Neso also holds the accolade of being the greatest distance away from its planet, orbiting at around 49 285 000 km from Neptune. It's thought that Neso and another moon - Psamathe - originated from the break-up of a larger moon long ago, due to their similar orbital paths.

Answer: False

Despite being classified as an irregular moon of Neptune owing to its retrograde (anti-clockwise) orbit and moderate distance from Neptune (around 355 000 km), Triton's orbit is almost perfectly circular. It's also much closer to Neptune than the other irregular moons; Nereid is the next furthest moon from Neptune, but orbits 5 513 818 km away - a far cry from Triton's comparatively measly distance.

Answer: True

Triton probably destroyed the original satellites of Neptune when it was captured and travelling on an extremely eccentric orbit. The leftover bits and pieces then accumulated to form the irregular, disc-shaped Thalassa. Thalassa is slowly spiralling towards Neptune thanks to tidal deceleration, and will eventually crash into Neptune's atmosphere... or perhaps break up into another Neptunian ring.

Answer: Greek mythology

All of Neptune's moons are named after Greek water deities, and quite a few of Neptune's moons - such as Galatea, Psamanthe, Neso and Sao - receive their names from the Nereids, who, in Greek mythology, were the 50 nymph children of Nereus and Doris. This is in contrast to Neptune, which was named after the Roman god of the sea (a parallel to Poseidon, the Greek of the sea).

Answer: 5

Voyager 2 discovered Naiad, Thalassa, Despina, Galatea and Proteus in 1989, all inner moons of Neptune - that is, they orbit relatively close to Neptune. These moons are quite dark, reflecting very little light, and are hypothesised to be made up of rubble left behind from original satellites of Neptune that collided with Triton when it was first captured into a very eccentric and wild orbit.

Answer: Naiad and Thalassa

Naiad and Thalassa are the two innermost moons of Neptune, orbiting 48 227 km and 50 074 km from Neptune, respectively. Despina is assumed to be a 'shepherd' moon of the LeVerrier ring: it orbits WITHIN this ring, not between it and the Galle ring. Galatea, another inner moon, orbits within the Adams ring - the brightest of all Neptune's rings.

Answer: Pharos

Pharos is the only surface feature of Proteus that's been given a name. Pharos is about 10-15 km deep and is named for the island where Proteus's namesake, a Greek shape-shifting sea god, reigned. Proteus is also lined with valleys and grooves, as well as many, many more craters with varying diameters.