Understanding exoplanet transit
Watch a planet cross a star and reveal the dip in brightness astronomers look for.
The idea behind it
A transiting planet hides a fraction of its star’s visible disk. Larger planets block more light. The light curve plots the remaining brightness as the planet moves across the star.
The relationship to remember
Planet/star radius = 0.1026. Central full-overlap depth would be 1.052%; the chosen path gives a maximum 1.052% dip.
Make your own discovery
Compare Earth-sized and Jupiter-sized presets. Notice how much harder it is to detect the smaller planet.
Try the interactive lab ↗What this model leaves out
An opaque circular planet, a uniformly bright star, and a straight path. Overlapping disk areas handle grazing transits. No limb darkening, starspots, noise, or orbital-speed effects.
Check your understanding
Does every planet transit?
No. The orbit must be aligned so that the planet passes in front of the star from our viewpoint.
Can a transit reveal a planet’s mass?
A transit primarily constrains size relative to the star. Mass usually requires additional observations.
Continue with the formula reference or test yourself in space practice.