Presentation #303.01 in the session Rubin Prize Lecture.
The population of transneptunian objects (TNOs; also known as Kuiper belt objects) in the outer solar system has a very complex orbital structure. The cold classical TNOs reside on low-eccentricity and low-inclination orbits from ~42-47 au and have distinctive physical properties (including very red surfaces, high rates of binarity, and a lack of very large objects) that imply they are an in situ remnant of the original planetesimal disk. The rest of the TNOs have much more dynamically excited orbits that extend out to hundreds or a few thousand au. The dynamically excited TNOs likely formed in a much more massive planetesimal disk interior to Neptune’s current location, were transported outward during the epoch of giant planet migration and have experienced ~4 Gyr of subsequent dynamical sculpting. I will briefly review our current best understanding of how these populations were emplaced, identify open questions about the details of giant planet migration in the early solar system, and discuss the particularly intriguing population of so-called ‘extreme’, high-perihelion and high-semimajor axis TNOs. I will present some recent and ongoing work to combine dynamical modeling with TNO observations to constrain both the past evolution of the giant planets and the limits of their current dynamical reach into the most distant TNO populations. I will also preview the development of user-friendly dynamical characterization software that will allow the small body community to fully leverage the expected deluge of new discoveries from LSST.