![TOI-1408 b: 2.2 Times Jupiter](https://cdn.slatesource.com/e/3/a/e3afd96b-e615-4416-9c76-7f46bf8cd2b9.webp) # TOI-1408 b: 2.2 Times Jupiter - [Made in Slatesource](https://slatesource.com/@steph/toi-1408-b-2-2-times-jupiter) - By [Steph](https://slatesource.com/@steph) - Created on Sep 19, 2026 ## Gas giant around TOI-1408 It is 2.23 times Jupiter's radius, closest in size to Jupiter, and 593.0 times Earth's mass, at 0.18 g/cm3, less dense than Earth. A year there lasts 4.43 days, on an orbit 7 times closer to its star than Mercury is to the Sun. Its equilibrium temperature is 1388 K (derived from the star rather than measured), hot enough to melt lead. The host star TOI-1408 runs at 6117 K with 1.31 times the Sun's mass. Radius 25.00 Earth radii Mass 593.0 Earth masses Equilibrium temperature 1388 K (derived) One year 4.43 days Orbit radius 0.0578 AU Host star TOI-1408 at 6117 K Distance 455 light-years Starlight blocked 2.239% at each transit **2.2x** Jupiter: among the largest planets measured 🔭🪐📅01.01.2023 – 01.01.2024 01.01.2023TOI-1408 b 01.01.2023 01.01.2024TOI-1408 c 01.01.2024 The state of the record for this planet 0% A measured radius. Yes. A weight, not just a width. Yes. A density, so rock and gas can be told apart. Yes. A semi-major axis. Yes. A measured temperature rather than a derived one. No. The shape of the orbit. Yes. What you get from the shadow The depth of the dip is the ratio of the two discs, so the radius follows. The archive lists no measured equilibrium temperature for this planet. The 1388 K quoted here is derived from the star's output and the orbital distance, assuming a third of the light is reflected. It is an estimate from two numbers, not an observation. A transit gives the radius and a separate measurement gives the mass. Having both is what makes a density, and a density is the only clue to composition at this range. TOI-1408 has 2 known planets. Planets in company tug on each other, and those tugs are measurable, which is how masses get pinned down without a wobble. Found by Transiting Exoplanet Survey Satellite (TESS) in 2023. TESS scans most of the sky in 27-day stretches, so it favours bright nearby stars and short orbits over the faint distant ones Kepler specialised in. # Half the temperatures quoted for exoplanets are calculated from the star, not \\ measured at the planet. Should a page like this show them at all, or leave the field blank? No comments yet. Be the first. Log in to comment [NASA Exoplanet Archive: source data, including the values not used here](https://exoplanetarchive.ipac.caltech.edu/overview/TOI-1408%20b?utm_source=slatesource)