How to Measure the Size of a Planet

Two thousand four all we knew about this thing was how long it took to go around its sun and how massive it was. But then, like seven years later, we got better telescopes, and we trained them on the star. And we were able to measure the size of this planet by seeing it eclipsing its star. They would have the same gravitational effect on the star, right? They would wiggle the stars in the same way. This is very different, because the planet is much, much smaller than the star.