Where is the edge of our Solar System? Or better yet, let’s say where is the outermost boundary of the Solar System?

Where is the edge of our Solar System? Or better yet, let’s say where is the outermost boundary of the Solar System?
Are we alone? Well, that’s the biggest question in science that I can think of anyway. So what’s the answer? Well, the short answer is “We don’t know.” Let’s dig more on today’s #365DaysOfAstro
How do scientists determine the characteristics of an exoplanet and made its illustration if they never have visited it?