Did Eris Once Hide an Ocean Beneath Its Surface?
Eris, a large Kuiper Belt object, likely once had a subsurface ocean that helped explain its current orbital state with its moon Dysnomia. Modeling by Akiba and Nimmo shows that spinning down Eris without an ocean is very difficult, while oceans appear in most successful scenarios. Though such oceans may have since frozen, insulation by porous ice, clathrates, or antifreeze like ammonia could have sustained them for billions of years.
Methane from the Beginning: A Primordial Origin for Methane on Eris and Makemake
Mousis et al. argue that the methane on Eris and Makemake likely formed in the early Solar System’s protosolar nebula, based on their high D/H ratios. Using disk chemistry models, they show that the methane’s isotopic signature matches a primordial origin, not internal production. This supports the idea that many outer Solar System bodies share common icy building blocks.