Exoplanet Transit Simulator

Kepler discovered ~2600 confirmed exoplanets using transits. The method is biased toward large, close-in planets with edge-on orbits - most planets never transit from our line of sight.

When a planet crosses in front of its star, it blocks a sliver of light — the depth of the dip equals the ratio of their disk areas, (Rp/R★)². So the light curve hands you the planet's size directly, with no image required. A Jupiter-sized planet dims a Sun-like star by about 1%, while an Earth-sized one dims it by only 0.008% (roughly 84 ppm).

During a transit the planet first hides the half of the spinning star rotating toward us, then the half rotating away, warping the star's measured velocity — the Rossiter–McLaughlin effect. The distortion's shape reveals whether the planet orbits with the star's spin or against it. Astonishingly, some hot Jupiters orbit backward: WASP-17b, confirmed in 2009, was the first known retrograde exoplanet.