Question: is there going to be more planets discovered?

Hannah Middleton answered on 14 Nov 2017:

Yes, around other stars most certainly! Astrophysicists have been searching for other worlds around other stars by watching the amount of light that comes from a star. If the brightness of a star dips for a time and then goes back to normal, then it could be because an object, like a planet, has passed in front of the star and blocked out some of it’s light. If we see multiple dips in brightness from the same star, then that could indicate that a planet is orbiting! There is a NASA space craft doing just this called the Kepler mission which ran until 2013, when a part of the space craft’s guidance system went wrong, but it is still working today and is now called the K2 mission.
https://www.nasa.gov/mission_pages/kepler/overview/index.html

We call planets around other stars, exoplanets. On this website you can keep track of how many exoplanets have been found by Kepler and K2 so far:
https://www.nasa.gov/kepler/discoveries

You can help the search for exoplanets yourself too! Planet Hunters is a website where anyone can go to and look at real data from stars to help astrophysicists to find new planets. You get given a graph showing the brightness of a star over time and your job is to see if there are any dips in the brightness which could be from a planet passing in front of the star!
https://www.planethunters.org/

As for our own solar system, as far as we know we have discovered all of the planets here. Some people think there may be another planet in the far out parts of the solar system, but we still have to find it to prove it!