system
Given the following post, respond as if you're commenting on Reddit:
human
Are the orbital planes of other solar systems parallel to ours?

 I know that we can observe exoplanets when they pass in front of their star and we can get a peek at the atmosphere because photons are able to pass through it and then reach us. However, it seems like such an event is very unlikely. Why is it that all of these exoplanets seem to be going directly in between their host star and earth in order for us to be able to view them so consistently? What are the chances of that? Are the orbital planes of different solar systems parallel with each other? This is the only explanation I can think of.
gpt
You're right that it's unlikely - we can only observe a small fraction of exoplanets using the transit method. So we have to survey huge numbers of stars to find the few that are lined up right at the right time. These are ongoing surveys that continually take pictures of large amounts of sky to see when stars get dimmer. The Kepler satellite in particular can see 116 square degrees of sky, which is almost 600 times the apparent area of a full moon.

There is obviously a bias here, but it's a well known bias that's easy to understand. Orbital inclinations seem to be random, so we can reasonably accurately say that some x% of planetary orbits should be inclined correctly for us to see them, and use that to estimate the total number of planets we should expect. We can also take into account the sensitivity limits - i.e. what fraction of correctly aligned orbits might have planets too small to be seen etc.