Planets exhibit extraordinary diversity in physical properties and orbital architectures, spanning more than four orders of magnitude in mass, separation, and age. Interpreting this landscape is challenging as observational biases and orbital migration obscure the pathways of planet formation and evolution across both space and time. While the full picture remains incomplete, a story is emerging for gas giants from radial velocity surveys probing planetary systems from the inside out and high-contrast imaging from the outside in. These complementary approaches are converging at intermediate scales, enabling a more continuous view of giant planet populations. I will present results from recent ground- and space-based efforts to constrain how giant planets assemble and evolve, with a focus on what direct imaging techniques are revealing about accretion disks, population demographics, orbital eccentricities, and stellar spin–orbit alignment. Together, these observations are informing the processes of gas accretion, angular momentum exchange, and dynamical evolution that shape planetary systems. I will also highlight how upcoming astrometric discoveries from Gaia—which is expected to reveal thousands of giant planets at intermediate separations later this year—will help bridge the gap between inner and outer planet populations and clarify how giant planets form and interact over time. These systems will also help establish the most promising nearby stars capable of hosting stable habitable-zone terrestrial planets, a central goal of future missions such as the Habitable Worlds Observatory.

Speaker: Brendan Bowler (University of California, Santa Barbara)

The 2026 Spring Colloquium talks are held on Wednesdays at 3:00 PM. This colloquium is hosted by STScI and will be held as an in-person and virtual event.

You may join in person at STScI’s John N. Bahcall Auditorium or virtually on the STScI Research YouTube channel.

Please direct questions or comments to contact above. The 2026 Spring Colloquium members are: Nimisha Kumari (STScI), Elena Manjavacas (STScI), Jack Neustadt (JHU), Kevin Schlaufman (JHU), Adam Smercina (STScI), Ethan Vishniac (JHU).