Why do astronomers find it hard to locate extra solar planets with telescopes?

Answer 1

Because they're extremely far away, and they're almost impossible to see visually because the star itself blocks out any light reflected by those planets. However, it is possible to detect them. One simple way is by seeing how the star's light diminishes when one or more of those planets pass in front of them. Or, if their orbits aren't lined up right for us to observe this, we can detect the subtle gravitational "wobble" caused by the presence of those planets. It's a difficult and time-consuming process, but it has paid off - we now know of hundreds of these "exo-planets."

Answer 2

Such planets:* Are very faint, i.e., they emit very little light.

* Are outshone by the stars they orbit, which are very close (in angular distance) to the planets.

Answer 3

For roughly the same reason that you might find it difficult to study a mosquito
that's circling an inch from a street light 10 blocks away.