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For Students · Exoplanet Transit

Exoplanet Transit for a galaxy rotation

Built for students learning it for a class or exam. See the concept move instead of memorizing formulas — and check your homework intuition. Simulate a galaxy rotation live below — adjust the inputs and watch it respond, right in your browser.

Exoplanet TransitLive

the transit method · light curves

Controls

Speed1×

Presets

Planet/star radius (Rp/Rs)

Impact parameter b

As a planet crosses its star, it blocks a tiny fraction of the light — a dip of depth (Rp/Rs)². This is how Kepler and TESS have found thousands of exoplanets. Impact parameter sets how centrally the planet crosses, changing the transit shape and duration. Drag the planet across the star to set its phase, or up and down to set the impact parameter — the light curve updates live.

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Data Inspector

Transit depth1.00%

Rp/Rs0.10

Impact b0.20

Governing equation

\frac{Δ F}{F} = (\frac{R _{p}}{R _{⋆}})^{2} = (0.10)^{2} = 1.00%

Reading this result: The dip depth is almost exactly (Rp/Rs)², so measuring how much light is blocked directly gives the planet's size relative to its star. The width of the dip is the transit duration, which — combined with how often it repeats — follows from the planet's orbital period and speed across the disk.

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Frequently asked questions

Is this good for students?: Yes — this version of "Exoplanet Transit for a galaxy rotation" is framed for students learning it for a class or exam. See the concept move instead of memorizing formulas — and check your homework intuition.
Do I need to install anything?: No. It runs in any modern browser, free, with no account required.