system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can we discover planets that are so far away?

I always wondered how can we find those planets that are light years from Earth.
gpt
Usually exoplanets are discovered by looking for a characteristic wobble of stars in a telescope.

Because gravity from planets will affect the spin of their star, stars with planets will appear to wobble back and forth compared to other, naked stars.

Then, by calculating the expected size of the star and the size and frequency of the wobble, they can make an educated guess as to the size and distance of the exoplanet from their star, or even if there are multiple exoplanets.