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Find a planet in a missing glimmer.

Exoplanet transit

Watch a planet cross a star and reveal the dip in brightness astronomers look for.

Exoplanet transitInteractive model
Light curve · dip depth vertically enlarged
Maximum depth1.052%
Light received98.948%
Radius ratio0.1026

Your experiment

Planet/star radius = 0.1026. Central full-overlap depth would be 1.052%; the chosen path gives a maximum 1.052% dip.

How it works

Central transit depth ≈ (planet radius / star radius)²

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.

Read the field note ↗

About this model
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.

Keep wondering

Exoplanet transit: common questions

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.

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