Physics

Exoplanet Discovery Calculator

Find the transit depth a planet produces crossing its star.

Calculated Output

Transit depth (%) 0.0084

Transit depth (ppm) 83.709

Formula: depth = (R_planet ÷ R_star)²

Step-by-Step Breakdown

1. Values used:

2. Planet radius = 1 R⊕

3. Star radius = 1 R☉

5. Transit depth = 0.0084%

6. Transit depth = 83.709ppm

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The math behind it

Transit depth = (R_planet ÷ R_star)², the fraction of the star's disk the planet blocks.

An Earth across a Sun-like star → about 84 ppm (0.0084%).

Why are Earth-like planets hard to find?

Their transit signal is minuscule — under 100 parts per million.