Orbital Period
Transit Properties
Instructions
- Adjust planet size for depth
- Change impact parameter for duration
- Watch light curve shape change
Watch a planet transit its star and measure the light curve—infer planet radius from transit depth
Explore transit photometry and exoplanet detection
The transit method detects exoplanets by measuring the tiny dip in starlight when a planet crosses in front of its host star. This technique has discovered thousands of exoplanets, including Earth-sized worlds in habitable zones. The depth, duration, and shape of the transit light curve reveal the planet's size, orbital period, and orbital geometry.
Transit depth δ ≈ (R_p/R_*)² gives the planet-to-star radius ratio. Duration depends on impact parameter b (how centered the transit is) and orbital speed. The probability of observing a transit is small—only planets with orbits aligned edge-on to us transit. For hot Jupiters, this probability is ~10%; for Earth-like planets at 1 AU, it's ~0.5%.