Triton, Neptune’s largest moon, hasn’t been studied in detail since Voyager 2 did a flyby in 1989. That was until a team headed by Will Grundy, a Lowell Observatory planetary scientist, did a 10-year study into the distribution of the moon’s ices.
Soon to be published in the journal Icarus, the team has found that concentrations of nitrogen and carbon monoxide mix together and form a covering of ice on the Neptune-facing side of Triton. This is in contrast to the methane content of the atmosphere. For some reason, methane is concentrated on the non-facing Neptune hemisphere of the moon. It appears that methane doesn’t like to mix with the other volatile ices.
This is in stark contrast to the non-volatile ices, such as water and carbon dioxide. Both appear to have a homogeneous distribution, regardless of phase or geographical location.
These are incredible observations of a moon that was once a Kuiper Belt Object. However, the infrared analysis carried out on Triton could be a test-run before observations are carried out on other, more exotic, targets.
“This type of long-term, detailed analysis would be equally valuable for small icy planets like Pluto, Eris, and Makemake, all of which are similar to Triton in having volatile ices like methane and nitrogen on their surfaces,” said Grundy. “We have been monitoring Pluto’s spectrum in parallel with that of Triton, but Eris and Makemake are quite a bit fainter. It is hard to get time on large telescopes to monitor them year after year. We expect that Lowell Observatory’s Discovery Channel Telescope will play a valuable role in this type of research when it comes on line.”