Sample Open Questions in Exoplanet Science:

(If you would like to use the wiki to expand on any of these, please add a link to a separate page for discussion.)


  • dynamical tides in general
  • thermal tides & synchronization
  • pseudo-synchronization for eccentric planets
  • role of tides on stellar host
  • Tidal Q and effects (and plunging)
  • Where is the heat deposited?
  • Effects on spins of planets and stars
  • Angular momentum alignment


  • formation at large distances to explain recently directly-imaged planets
  • Planetesimal growth through the 1-meter bottleneck
  • Terrestrial, ice giant, and gas giant formation, relative fractions, and orbital distributions
  • Core accretion vs. direct collapse models of giant planet formation - evidence for dense cores
  • Brown dwarfs and brown dwarf desert( ?)
  • Distinction between BDs and EGPs (IAU vs. origins; discriminants)
  • Zodiacal light distribution (re TPF, patchiness, etc.)
  • Gravitational Instability
  • Cluster environment within which planetary systems form


  • Gas accretion during migration
  • What halts migration?
  • how can massive palnets be "pushed"?
  • role of disk turbulence (MRI, dead zones)
  • role of disk thermodynamics (horseshoe drag)
  • T-Tauri spin connection
  • Holes in Disk

Orbital Dynamics

  • generality of planet-planet scattering process (Solar System vs. exosystems)
  • "Nice" model
  • Resonances, stability
  • Architecture
  • Effect on Habitability

Planetary Structure & Evolution

  • super-Earths vs mini-Neptunes, can we tell the difference?
  • Equations of state for planets
  • Radius vs. Mass
  • Rotational effects (especially on gas giants)
  • Solid-body and gaseous convection
  • How to explain the large radii of some EGPs?
  • The dynamics - structure connection


  • different approaches to circulation regimes & validation
  • Non-equilibrium atmospheric chemistry (e.g. CO_2)
  • Thermal inversions and causes (correlation with zonal winds, hot spots)
  • Zonal flows, heat redistribution
  • Day-night contrasts
  • Mechanism of dissipation in exoplanet atmospheres
  • Climate, 3D effects
  • Spectral signatures of life [biosignatures] (non-equilibrium biotic chemistry, red edge, ....)
  • Temporal variation of atmospheres and spectra
  • Evaporation


  • Habitable zones
  • Biosignatures
  • The effects of terrestrial planet mass on habitability
  • dynamical and orbital effects on habitability


  • Star-planet compositional differences
  • Lithium depletion in stellar atmospheres (and evidence for planet consumption by star)
  • Magnetic field diagnostics and effects
  • Moon and Rings