Why we can accurately detect stars billions of light years away, but we can’t confirm if we have a 9th planet in our solar system?

Question

Why we can accurately detect stars billions of light years away, but we can’t confirm if we have a 9th planet in our solar system?

In: 2123

Answer 1

I think part of the problem is that most pictures showing our Solar System aren’t to scale. If you were an outside observer looking at the Solar System, you’d have a very hard time spotting any planets. The distance between our small-to-scale planets is also very, very large. It’d be like dropping a black marble into the Marianas Trench and trying to spot it on the bottom from the surface.