The Terrifying Size of the Biggest Planet We’ve Ever Found

What is the largest planet we've ever found? It sounds like the simplest question in astronomy - but the answer breaks apart the moment you reach for it. The biggest planets ever detected aren't just enormous. They're so extreme that astronomers can't agree on whether some of them should even be called planets at all. In this documentary, we explore three extraordinary objects that each claim the title in a different way. HAT-P-67 b - a confirmed gas giant inflated to twice Jupiter's width but with a density lower than marshmallows, slowly losing its atmosphere to a dying star. ROXs 42 B b - a young, blazing giant in a stellar nursery whose size is estimated from models, not measured from transits, and whose very classification as a planet depends on which definition you use. And HD 100546 b - a wild-card protoplanet candidate still embedded in the disk where it is forming, with an apparent radius so large it defies belief, but uncertainties so wide that it may not be a finished world at all. Sources: Zhou, G. et al. (2017). "HAT-P-67b: An Extremely Low Density Saturn Transiting an F-Subgiant Confirmed via Doppler Tomography." The Astronomical Journal, 153(5), 211. https://doi.org/10.3847/1538-3881/aa6481 Currie, T. et al. (2014). "Direct Imaging and Spectroscopy of a Candidate Companion Below/Near the Deuterium-Burning Limit in the Young Binary Star System, ROXs 42B." The Astrophysical Journal Letters, 780(2), L30. https://doi.org/10.1088/2041-8205/780... Quanz, S.P. et al. (2015). "Confirmation and Characterization of the Protoplanet HD 100546 b — Direct Evidence for Gas Giant Planet Formation at 50 AU." The Astrophysical Journal, 807(1), 64. https://doi.org/10.1088/0004-637X/807... Spiegel, D.S., Burrows, A. & Milsom, J.A. (2011). "The Deuterium-Burning Mass Limit for Brown Dwarfs and Giant Planets." The Astrophysical Journal, 727(1), 57. https://doi.org/10.1088/0004-637X/727... #LargestPlanet #Exoplanets #SpaceDocumentary #HATP67b #PlanetaryScience #JamesWebbSpaceTelescope #DeepSpace