system
Given the following post, respond as if you're commenting on Reddit:
human
If we can find hundreds of exoplanets orbiting stars hundreds of light-years away, why do we have a hard time conclusively confirming Planet Nine within our own solar system?
gpt
That's not an ideal comparison for a few reasons:

-There are billions of stars to look at, a small fraction have detectable planets but most of them do not. There is only one sun so we can't get statistics on multiple versions of our solar system.

-Most planets are detected by the light they block as they pass in front of their host star. That doesn't work for something farther from the sun than the Earth.

-Most planets we detect have very short orbits compared to our solar system, so that periodic signals can be observed. Planet Nine is expected to have an orbit of thousands of years.