Is there a mysterious undiscovered Planet?

Is Planet X a planet, or something else? Why do Astronomers think there's a mysterious Planet beyond Pluto? Why haven't we found Planet X yet? Grown-Ups: Be a better you in 2024 with Babbel, the science-backed language-learning app that actually works. Get 55% off at Babbel.com/SMARTED. Rules and restrictions may apply. Say hello to HelloFresh! Go to HelloFresh.com/smartedfree and use code: smartedfree for FREE breakfast for life! One breakfast item per box while subscription is active. Getting a good night's sleep can make all the difference to your day. That's why the Trusty Narrator loves Boll and Branch sheets- and so do millions of other people. Boll and Branch make the softest, most luxurious sheets - with no toxins or harsh chemicals to make them seem "softer". Thread count can be deceptive - but these are 100% organic cotton that can be traced from family farm to your family home. These sheets are so great that they actually get softer and more luxurious with every wash. You can try them worry-free with their 30-day no questions asked money back guarantee, including free shipping. Even better- the SmartyFamily gets 15% off with promo code SMARTED. Go to BollAndBranch.com and start sleeping better - you deserve it! Hydration is so important whether you’re an athlete, parent-on-the-go, or busy with work - or all three! The Trusty Narrator loves LMNT, the sugar-free electrolyte powder that replenishes your hydration without all the artificial ingredients in so many other hydration powders. And it’s not just Trusty - many Olympic athletes and professional sports players rely on LMNT too! You’ll get a free sample pack of their flavors with your first order with our special code DrinkLMNT.com/WhoSmarted . They offer a 100% money-back guarantee-if you don’t love LMNT as much as we do, you’ll get your money back and you don’t even have to return the product! Have you started your FREE TRIAL of Who Smarted?+ for AD FREE listening, an EXTRA episode every week & bonus content? Sign up right in the Apple app, or directly at WhoSmarted.com and find out why more than 1,000 families are LOVING their subscription! Get official Who Smarted? Merch: tee-shirts, mugs, hoodies and more, at Who Smarted?