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Moons of our Solar System
Moons of our Solar System

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3.9 The New Horizons mission

Described image
Figure 61 Global view of Charon and a close-up obtained at a range of only 79,000 km. 

Pluto’s moons were revealed in detail in 2015 when the New Horizons mission flew past Pluto. Launched in 2006, its journey to Pluto took nine years, and radio signals transmitted back to Earth took about four-and-a-half hours to reach us. It showed that Pluto’s landscape is unlike that of Triton, even though they have similar compositions. Charon has a mixture of cratered (old) terrain and smooth (young) terrain that might have been cryovolcanically resurfaced, and is cut by major fractures.

Despite searching, New Horizons did not find any new small moons, but it did discover that the rotation axes of the four previously-known small moons point in various directions and that their rotation periods are much shorter than their orbital periods (so these are not in synchronous rotation, unlike Charon). Here are views of Nix and Hydra shown at similar scales.

Described image
Figure 62 Nix (left), 42 km long and Hydra (right), 55 km long. The colour on Nix has been exaggerated to highlight an unexplained red area.

You can follow the mission at this link: New Horizons [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)]

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