Final answer:
We use indirect detection techniques like the Doppler and transit techniques to reveal things that we can't see with our eyes alone, such as rogue planets.
Step-by-step explanation:
We use indirect detection techniques to reveal things that we can't see with our eyes alone, such as rogue planets. One of the most powerful indirect tools for finding exoplanets is the Doppler technique. This technique allows us to observe the gravitational tug of an unseen planet on its host star, causing a small wobble in the star's motion. Another technique is the transit technique, where a planet periodically crosses in front of its star, causing the brightness of the star to dim.