Similar to the Media section, by moving the Planets section into Science, it creates a more concise way for users to search (i.e. no need to check Science, and then go back and look for another section to cover what they are looking for).
The Media category was becoming too vague and too cluttered with items that fell into other, already existing, categories. By breaking up this category, we are able to allow viewers to quickly find what they need, instead of making them search the category they want and then have to double-check the "catch-all" basin that was Media.
Dave Machado