In honor of Earth Day, The Simpsons has a brand-new episode available (and only available) on Disney+.The direct to streaming episode is called “Yellow Planet” and, fittingly, it is a spoof of National Geographic-style documentaries series. (National Geographic, like The Simpsons, is owned by Disney. Mmmm ... corporate synergy.) So in “Yellow Planet,” you’ve got Homer reimagined as a whale, Bart as a lizard, Lisa as a bird, and so on. (If you don’t like nature docs, some of the jokes might be a bit obscure. Then again, when you cast Homer as a whale, I suppose some of the gags sort of write themselves at that point.)Here’s a trailer for the special Simpsons episode:READ MORE: Every Simpsons Chalkboard Gag Ever, RankedHere is the episode’s official synopsis:In “Yellow Planet,” The Simpsons are reimagined as animals in a National Geographic-style nature mockumentary. Homer and Marge navigate the ocean as whales from different series, Bart hatches as an iguana struggling to survive, and Lisa leads her flock as a finch. Along the way, familiar Springfield faces appear in unexpected roles, shaping their journeys in the wild.The exclusive “Yellow Planet” episode of The Simpsons is now streaming on Disney+, along with 35 earlier seasons of the series, The Simpsons Movie, and over 10 other Simpsons Disney+ shorts. If you are curious: There are now almost 800 episodes of The Simpsons and, with the series currently in its 36th season, Fox has already renewed it through its 40th season.40 years of The Simpsons?!? Unbelieveable.Sign up for Disney+ here.Get our free mobile appTV Shows We Used to Love That Are Cringe NowWe can't say why we liked these shows, but we can certainly say why we can't watch them now. Gallery Credit: Emma Stefansky