Q126Comprehension2 Marks7 Aug 2022
Passage
Triton is the largest natural satellite of the planet Neptune, and was the first Neptunian moon to be discovered. The discovery was made on October 10, 1846, by English astronomer William Lassell. It is the only large moon in the Solar System with a retrograde orbit, which is an orbit in the opposite direction to its planet's rotation. Because of its retrograde orbit and composition similar to Pluto's, Triton is thought to have been a dwarf planet, captured from the Kuiper belt. Triton has a surface of mostly frozen nitrogen, a mostly water-ice crust, a icy mantle and a substantial core of rock and metal. The core makes up two-thirds of its total mass. Triton has a mean density of 2.061 grams per cubic centimeter, and is composed of approximately 15-35% water ice. Triton is one of the few geologically active moons in the Solar System, which means its surface is relatively young with few impact craters. It has active geysers erupting sublimated nitrogen gas, which forms a thin nitrogen atmosphere.
How does Triton orbit Neptune?