Question

Which orbital properties of extrasolar planets can be measured and what methods are used to make those measurements? Please do not hand write or post pictures as it is difficult to read.. thanks!

Answer 1

"The technique that has discovered the most extrasolar planets, the transit method, involves looking at dips in the observed brightness of stars caused by a planet passing in front of them and blocking the light. The amount in which the brightness drops can tell us how much of the star is being blocked, which lets us know the size of the planet. Since the planet will only block its star once every orbit, by looking at how often this happens we can also determine the planet's orbital period."

"Another detection method that has found many exoplanets is the radial velocity method. When a planet orbits a star, it also exerts a slight gravitational tug on the star, causing it to wobble. This method involves looking for wobbling stars that indicate orbiting planets. By looking at how much the star wobbles, it's possible to tell how massive the planet is; the more massive the planet, the larger the wobble that it causes. By measuring how the strength in the wobbles changes over time, it is also possible to determine the orbital period of the planet."