Question

there are 9 planets in the universe or 8

Answer 1

There are 8 planets.
Mercury, venus ,earth, mars, jupiter, saturn, uranus, neptune.
pluto is not considered as a planet. Usually it is referred as dwarf.
Hope it helps u!!

Answer 2

Firstly your question is wrong You have to ask that it is in our solar system but You said universe ....
There is so much universe left that u can't imagine....so i will tell u this answer in the observable universe....

Our solar system consist of 11 to 12 or more planets because many are not discovered and planets are revolving our solar system ...
so after Pluto I can tell u which planner is revolving....
their are 8 planets in solar system because the planets inside it have a distance which is basically and others are not considered because they are far away from distance which are set by the scientist...

So Eris is the 10th planet in our solar system and their are more which are revolving the sun.....