Exoplanet Transit Depth Calculator
Exoplanet Transit Depth
Calculate the expected transit depth, duration, and probability for an exoplanet transiting its host star based on planetary and stellar radii and orbital distance.
Formula
Transit Depth = (Rp / Rs)^2; Transit Duration = (P / pi) x (Rs / a); Transit Probability = Rs / a
Frequently Asked Questions
What is transit depth?
Transit depth is the fractional decrease in observed starlight when a planet passes in front of its host star. It equals the square of the ratio of the planet radius to the star radius.
How much does Earth dim the Sun during transit?
Earth would cause a transit depth of about 0.0084 percent, dimming the Sun by 84 parts per million. This is detectable by space telescopes like Kepler and TESS but very challenging from the ground.
What determines the transit probability?
The geometric transit probability is approximately the ratio of the star radius to the orbital distance. For Earth-like planets around Sun-like stars, the probability is only about 0.47 percent.