[jbird11]

I've always wondered, what determines which planet or solar system to observe? I guess I'd like to think we have a list of solar systems that are most likely to hold life and simply go down it from most likely to least likely but it surely can't be that reductive.

[sharlos201068]

My understanding is that most Earth-sized exoplanets these days are detected using telescopes performing a wide survey of entire sections of the sky, tracking periodic changes in the star's brightness or position (if the planet makes the star wobble).

So they aren't really picking out specific stars intially. Once they've identified a candidate exoplanet, then they'll often try to confirm it using more direct/targetted observations.