“Like an archaeological dig into the history of our Solar System.” That’s how New Horizons principal investigator Howard Stern described the spacecraft’s mission to Pluto and the outer Solar System. In recent decades, our ability to peer into the murky edges of the Solar System and map the populations of icy bodies that reside there has not only changed our understanding of the true scale and nature of the Solar System, but has also shone a light on the past, on how the current arrangement of rocky and icy worlds came to be and how interactions with the wider galaxy might shape its future.
Residents of the outer Solar System can be divided into various populations by their current orbits, history of orbital interactions or their compositional makeup. Kuiper Belt objects (KBOs) are the first population encountered as you move beyond the orbit of Neptune at around 30 astronomical units (AU) – one AU is the Earth-Sun distance. This sparsely populated ring extends out to 2,000 AU and includes icy bodies left over from the formation of the Solar System. Larger residents include Pluto, as well as Eris, Makemake and Haumea, which along with many much smaller inhabitants form a large subgroup known as ‘hot’ Kuiper belt objects.
WORLDS BEYOND PLUTO
Haumea
Haumea’s combination of rings and moons is yet to be explained by astronomers.
Farfarout
In 2021 Farfarout was confirmed to be the most distant object ever observed in our Solar System.
Eris
Initially thought to be larger than Pluto,
