An Earth-sized planet crossing the solar disk dims the star by only about 0.008%, well under the measurement noise, so the signal has to be stacked out of many cycles. The depth tracks δ = (Rp/Rs)² with planet radius, and as the impact parameter b approaches 1 the flat bottom vanishes and the curve sharpens into a V. Phase folding averages the noise down until the dip finally stands clear.
An Earth-sized planet crossing the solar disk dims the star by only about 0.008%, well under the measurement noise, so the signal has to be stacked out of many cycles. The depth tracks δ = (Rp/Rs)² with planet radius, and as the impact parameter b approaches 1 the flat bottom vanishes and the curve sharpens into a V. Phase folding averages the noise down until the dip finally stands clear.
Related topics in Space