Masses and semimajor axes of known planets and simulated Gaia planets. In both cases, we have restricted the sample to planets with P_orb and m_p constrained to within 20% (i.e., P_84th/P_16th < 1.2 and m_84th/m_16th < 1.2). Blue and green points are real planets discovered with the Doppler and transit methods, respectively. Red and black points are from our mock Gaia planet catalogs for Data Release 4 (DR4) and Data Release 5 (DR5; see Section 4). For comparison, the values of Jupiter and Saturn are highlighted with gray points labeled “J” and “S,” respectively. The Gaia planets are primarily super-Jupiters on several-astronomical-unit orbits. About 100 such planets are currently known; Gaia promises to expand this sample to thousands in DR4 and tens of thousands in DR5.