Why are large extrasolar planets close to their stars easier to detect?

Large extrasolar planets that orbit close to their stars are easier to detect because the primary methods used to find them—radial velocity and transit photometry—are inherently most sensitive to these configurations.12

• Radial Velocity: This method detects planets by measuring the "wobble" or motion of a host star caused by the gravitational pull of an orbiting planet. A massive planet orbiting very close to its star exerts a stronger gravitational influence, inducing a more pronounced and detectable motion in the star compared to smaller or more distant planets.13
• Transit Photometry: This technique identifies planets by observing the periodic dip in a star's brightness as a planet passes in front of it. Large planets orbiting close to their stars are more likely to be detected because they block a larger portion of the star's light and have shorter orbital periods, leading to more frequent and observable transit events.12

Because these techniques favor large, close-in worlds, many of the first discovered extrasolar planets were "hot Jupiters"—massive gas giants orbiting very near their parent stars.13