It’s pretty much old news at this point. The International Astronomical Union has made up criteria for what it takes for a body to be counted as a planet and Pluto didn’t make the cut.
One impact of this decision is a lot of people wondering how long it’s going to take all the schools to get their textbooks and curricula up to date. It’s a bit of cynicism on my part, after all, it’s been 70 years since Pluto’s discovery, but I can’t help wondering how many schools have text books that have suddenly reverted to being correct.
I suppose there is some scientific merit to having a formal definition for what makes a planet. But there’s also a lot of sentiment for keeping Pluto on the books as a planet. Small wonder then that there are groups protesting.