What method is used to detect exoplanets by observing dips in starlight brightness?

The transit method is a prominent technique used to detect exoplanets by monitoring the brightness of stars over time. When a planet transits, or passes in front of its host star from our perspective, it causes a temporary dip in the star's brightness. This dimming occurs because the planet blocks a portion of the light emitted by the star.

By observing these periodic dips in brightness, astronomers can infer the presence of an exoplanet, as well as acquire valuable information about the planet's size and orbital period. The data collected can illustrate the frequency and duration of these transits, allowing scientists to identify not only the existence of the planet but also its relative size compared to the star it orbits. This method has been very successful, especially with space missions like Kepler, which have identified thousands of exoplanets using the transit technique.

While gravitational microlensing, radial velocity, and direct imaging are alternative methods used in exoplanet detection, they operate on different principles and are suited for different scenarios in the search for exoplanets.