The planets that are closer in physical size to their parent star and that are aligned with our line-of-sight to the star block a larger fraction of its light, enabling us to see it better. Get a Sun-like star with an Earth-like planet, and we wouldn’t be able to see it. The planets that are closer in mass to their parent star pull more strongly, and so are easier to measure. Image credit: ESO, under the Creative Commons Attribution 4.0 International License. Our limitations are that our current techniques were only really useful for measuring certain kinds of planets. and their orbital period (by measuring… their orbital period).their radius (by the amount of light that they block),.their mass (by the pull on their parent star),.Over the past generation, we’ve not only successfully found thousands of planets by multiple different methods, but we’ve been able to measure: “They must be there,” you’d reason, “since there’s no way our Solar System is unique in all the galaxy.” But where’s the proof? As the case always is in science, it’s in the data you collect and in the measurements and observations you make. If you had looked to the skies just 25 years ago, you’d only be able to wonder about planets around other stars. There’s no cure for that.” –Samuel Beckett Four years ago, the world was shaken with the announcement of a planet around Alpha Centauri.