Exoplanet Transit Lab

Transit Photometry Method

When an exoplanet crosses in front of its host star from our line of sight, it blocks a fraction of the star's light. This method, called Transit Photometry, is how telescopes like Kepler and TESS discover most exoplanets. Astronomers observe thousands of stars simultaneously, collecting brightness data over time to form a Light Curve. By analyzing the U-shaped dip in the curve, they can deduce the Occultation Depth. The depth is proportional to the square of the radii ratio: Depth = (R_p / R_s)². Because we usually know the star's size (from its spectrum), we can calculate the exact physical size of the alien world!