Planetary Transit Calculator

They move it in opposite directions but by the same relative amount: Transit Depth is literally (Planet Radius / Star Radius) squared, so growing Planet Radius deepens the transit while growing Star Radius shallows it, and a given percentage change in either input produces the same-size percentage swing in Transit Depth because both sit inside the same squared ratio. A Jupiter-sized planet around a Sun-sized star produces a dip roughly 100 times deeper than an Earth-sized planet around that same star, purely from the radius ratio.

It means the planet's disk misses the star's disk entirely from Earth's vantage point, even though this calculator still reports a Transit Depth, Duration, and Probability as if a transit were happening. Impact Parameter is (Semi-Major Axis / Star Radius) times the cosine of Orbital Inclination, so at a perfectly edge-on 90-degree inclination it is exactly 0 (a dead-center crossing), and it grows quickly as inclination departs from 90 degrees because most stars are tiny compared to a planet's orbital distance.

No. Transit Depth depends only on the ratio of Planet Radius to Star Radius -- how much of the star's disk the planet covers once it is in front of the star. Orbital Inclination instead controls whether a transit happens at all (via Impact Parameter) and, more subtly, how close to the star's center the crossing is, which this calculator's simplified duration formula does not fully model.

Transit Probability is Star Radius divided by Semi-Major Axis (in matching units), so it is a pure geometric ratio: a planet orbiting farther from its star sweeps out a much larger circle, and the star's disk covers a proportionally smaller sliver of the possible orbital-plane orientations that would produce a transit. This is why hot, close-in planets are found by transit surveys far more often than distant, cold ones -- not because they are more common, but because their transit geometry is far more probable to catch.

No -- it uses a simplified circular-orbit approximation (arcsin of Star Radius over Semi-Major Axis, scaled by Orbital Period) that assumes a roughly edge-on crossing and does not fully account for the crossing's Impact Parameter or orbital eccentricity. Real transit-duration calculations used in mission planning also fold in the planet's own radius and the exact impact parameter; treat this output as a reasonable first estimate, not a substitute for full orbital-mechanics software.